White background with no visible content.  VAN NOSTRAND'S SCIENCE SERIES. No. 17.--WATER AND WATER SUPPLY. By Pnor. W. H. Comperd, M.A., of the University College, London. No. 18.--SEWERAGE AND THE USE OF UTILIZATION BY PROF. W. H. Comperd, M.A., of the University College, London. No. 19.--STRENGTH OF BEAMS UNDER LOADS OF VARYING DURATION. By Prof. W. A. Allen, Author of "Theory of Aviation." No. 20.--BRIDGE AND TUNNEL CENTRES. By John M. McMathers, C. E. With Illustrations. No. 21.--SAFETY VALVES. By Richard H. Broughton, W.E.Illustrations. No. 22.--HISTORICAL DEVELOPMENT OF THE BRIDGE ART. By Joury R. McMathers, C.E. With Illustrations. No. 23.--THE FATE OF METALS UNDER THE ACTION OF WATER AND AIR. By Joury R. McMathers, C.E. With Tables of Results of Experiments, From the German Journal of Chemistry, Vol. XXVII., No. 56, 1895. No. 24.--A PRACTICAL TREATISE ON THE TERTIARY OF WHEELS, with the Theories of the Tertiary and Quaternary Periods, by S.W. Robinson, Prof. of Mechanical Engineering, Illinois Industrial University. No. 25.--THEORY AND CALCULATIONS OF BOILERS AND STEAM PUMPS. By Field Mermerman, C.E. With Illustrations. No. 26.--PRACTICAL TREATISE ON THE PROPERTIES OF CONTINUOUS BURNING OF OILS AND Gases, C.E. No. 27.--ON BOILER INSULATION AND CORROSION. By F.J. Rowan. A page from a book titled "Van Nostrand's Science Series" containing various scientific articles.  VAN NOSTRAND'S SCIENCE SERIES. No. 88.--ON TRANSMISSION OF POWER BY WIND ROPE. By ALEKSEY W. STREL. Fully illustrated. No. 89.--INJECTORS; THEIR THEORY AND CONSTRUCTION. By the French of M. Lacroix Poussin. Illustrated. No. 90.--TERRESTRIAL MAGNETISM. By JAMES H. BELL. Illustrated. No. 91.--THE SAILING SHIPS. By Prof. Fairman Rogers. Illustrated. No. 92.--THE SAVINGS BANKS; THEIR USE IN TOWN AND COUNTRY. By George W. Anderson, Esq., of Sanitary and Agricultural Works. No. 93.--CABLE MAKING FOR SUSPENSION BRIDGES; THE CONSTRUCTION OF THE EAST RIVER BRIDGE. By WILBUR MILLERHORNS, C. E. Pulley, illustrated. 15mo, boards, 50 cents each 1st Edition sent by mail on receipt of price. D. VAN NOSTRAND, Publisher, 63 Murray and 87 Warren Sts., New York.  FOUNDATIONS. LIBRARY OF THE UNIVERSITY BY J. J. HARRISON, D. CIVIL ENGINEER. TRANSLATED FROM THE FRENCH BY L. F. VERNON HARCOURT, M. A., Member of Institution of Civil Engineers. REPRINTED FROM THE NOSTRAND'S MAGAZINE. A circular emblem with a design of three interlocking circles. NEW YORK; D. VAN NOSTRAND, PUBLISHER, 30 MURRAY AND 51 WASHINGTON STREET. 1876.,  TAT15 G3 27439  P R E F A C E. This essay, from the pen of an eminent continental engineer, was presented, after translation into English, to the Institution of Civil Engineers of Great Britain by L. F. Vernon Harcourt, M.I.C.E. It was reprinted from the "Proceedings" of the Institution in *Von Nos-trand's Magazine*, Vol. XVIII. The importance of the subject and the eminence of the author justify the belief that, in the compact form of the Science Series, it will be an acceptable addition to engineering literature.  .  LIBRARY of the UNIVERSITY of CALIFORNIA FOUNDRY The Author proposes to give a description of the principal methods resorted to in making foundations. Although these methods are applicable, in general, to every sort of construction, they possess a special importance in the case of large buildings, account of the greatness of the load, the instability of the soil, and the amount and flow of water to be contended with. It is not sufficient, moreover, that the bed of the river and the ground upon which the foundations of a pier rest are firm, they must also be solid enough so as only hard rocks are unaffected by a rapid stream. To ascertain the nature of the soil on which foundations are to be laid borings are generally taken, but they sometimes prove deceptive, owing to  6 their coming on some chance boulders, or upon some adhesive clays which, without being firm, stick to the auger, and twist it, or arrest its progress, and the specimens brought up, being crushed and pressed together, look firmer than they really are. In consequence of this fact, some engineers have adopted a hollow boring tool, down which water is pumped and reascends, by an annular cavity between the exterior surface of the tool and the soil, with such velocity that not only does the water drive out the auger, but pebbles also, are lifted by it to the surface. This process is rapid, and the specimens, which are obtained without torsion, preserve their natural consistency. On stiff clay, marl, sand, or gravel, the safe load is generally from 50 to 110 cwt. on the square foot, but a load of 160 to 185 cwt. has been put upon close sand in the foundations of the Gorai bridge, and on gravel in the Loeh Ken viaduct and at Bordeaux. In the bridge at Nantes there is a load of 192 cwt. to  7 the square foot on sand, but some settlement has taken place. Under the cylindrical piers of the Szegedin bridge in Hungary, the soil, consisting of clay intermixed with fine sand, bears a load of 138 cwt. to the square foot; but it was deemed expedient to increase the supporting power by placing the cylinders in the interior of the cylinders, and also to protect the cylinders by sheathing outside. Cylinders, moreover, sunk to a considerable depth in the ground, possess internal resistance against the force of the weights required for sinking them, which adds greatly to the stability of the foundations. Taking into account this auxiliary support, the loads of 150 and 117 cwt. per square foot, at the bottom of the cylinders of the Charing Cross and Queen's Road bridges respectively, are not excessive. On a rocky ground the Roquesflavoue aqueduct exerts a pressure of 268 cwt. to the square foot. Foundations may be classed under two heads:—(1) Ordinary foundations, on  8 land, or protected from any considerable rush of water; (2) Hydraulio founda- tions, in rivers, or in the sea. ORDINARY FOUNDATIONS. When the ground consists of rock, hard mast, stiff clay, or fine sand, the foundations can be laid at once on the natural surface, or with slight excav- ation, and with horizontal steps where the ground slopes. At the edge of steep descents, with dipping strata, it is neces- sary to form a retaining wall, or to fill in, or if there is such a tendency, to strengthen the layers of rock by a wall, especially when it is liable to undergo decomposition by exposure to the air, or to use iron bolts uniting the layers of rock. On ground having only a super- ficial hard layer of clay or sand, soft subsoil, buildings have sometimes been erected by merely increasing the bearing surface, and lightening the superstruc- ture as much as possible; but generally it is advisable to place the foundations below all the soft soil. On an uneven A diagram showing a cross-section of a building foundation.  surface of rock a layer of concrete spread all over affords a level foundation. Sometimes large buildings have been securely built on quicksands, of two great thickness to be excavated, by the aid of excellent hydraulic mortar, and by excavating a trench below each bottom storey. Such a building will be stable if its pressure on the foundation is uniform throughout, and if it is placed sufficiently deep to counterbalance the tendency of the sand to flow back into the foundation. The most common cases of foundations are to be found in sewers built on water-bearing sands, which sometimes give rise to as much difficulty as foundations built in rivers; as for example in the net-work of London sewers, and in the Metropolitan railway. The swelling of these sands was prevented by pumping, and consequent undermining of the houses above, was prevented in these cases by constructing brick or iron sumps for the pumps in suitable places, surrounding them by a filtering bed of gravel, and using earthenware collecting  10 pipes, thus localising the disturbance. In the construction of the Paris sewers, where the water-bearing strata could not be examined, the first section of the lining in of the sand, the upper portion only of the culvert was first constructed (Fig. 1). A little trench was then dug Fig. 1. Fig. 2. SEWERS IN PARIS out at the bottom, each side being sup- ported by interlaced boards, and this trench was then pumped dry in lengths of about 30 feet. When one length was dry, a second row of boards was beaten down on the top of the first row, and at last it was possible to excavate the soil in lengths of thirteen feet, after which, owing to the lower portion and the invert could be constructed, completing the section of the culvert (Fig. 2). In this manner a  LIBRARY OF CONGRESS ouvert, nine feet ten inches wide, twelve feet six inches high, and seventeen long, was constructed in eighty-five days. The excavations for a sewer at Grenoble were executed from below upwards, in order to prevent the contamination of the water, and the sides were built as the excavation proceeded, a trench supported by boards conveying the water, and the invert was begun when the piers were finished, commencing at the upper part; sand being thrown on cement having been placed at the bottom of the trench to afford continuous drainage, over which a layer of quick-setting concrete was deposited (Figs. 3 and 4). Fig. 3. A diagram showing a cross-section of a sewer with a layer of quick-setting concrete deposited over a layer of sand. Fig. 4. A diagram showing a cross-section of a sewer with a layer of quick-setting concrete deposited over a layer of sand. SEWERS AT GRENOBLE One means of reaching a solid foundation without removing the upper layer of soft soil is by piling, but piles are like...  ble to decay in many soils. In Holland, buildings on piles of larch, alder, and fir have lasted for centuries, whilst in Belgium large buildings have been endangered by the decay of the piles on which they rest. The massive columns of masonry supporting the superstructure, but being placed farther apart than piles, it is necessary to connect them with arches at the surface for carrying the walls. Piers, however, of viaducts supporting a heavy load must be carried down in one mass to the bottom of the valley. This was done in the construction of the viaduct of Otaura, on the Rio Salera in Spain, where it was necessary to get through sixty-five feet of silty clay to lay the foundations of a pier thirty-one feet long by thirteen feet wide. In order to make getting out of such a large excavation in one piece, a well was dug, four feet wide, and extending across the whole width, thirteen feet, of the pier, so as to divide it into two equal portions (Fig. 5). A chamber, nine feet ten inches high, was then driven at the bottom, like a heading, as far as the 12  13 limits of one-half of the foundation of the pier, and built up with masonry. Fig. 5. OTZARTE The other half was similarly dealt with, and the excavation and masonry were carried up in successive lifts of nine feet ten inches. The central well served as a means of access for pumping out the  14 water, for the removal of earthwork, and for the supply of materials. To avoid the difficulty and expense of timbering deep foundations a lining of masonry is sometimes sunk, by gradually excavating the ground, and then filling with rubble stone, weighting the necessary cylinder, which is eventually filled in with rubble stone, concrete, or masonry, and serves as a pier. In India a similar system has been followed for centuries for sinking wells. The linings are made in radiating courses of bricks or stones; the first length, from five to ten feet high, being put on a circular wooden framework placed on the surface of the ground. Very fine sand is used for tying the joints, except for the two or three feet at each end which are laid in mortar, and the whole construction is tightly bound together. It is then gradually sunk by a man inside undermining it, and another length is placed on the top. As these operations are generally conducted in the siltly or sandy bed of rivers which become dry  15 in summer, there is no running water to contend with, but water percolates into the excavation, and then the natives use a "Jham," by which they remove the earth from under water. Although the external dimensions of the wall have been somewhat limited to five feet, the ad- vantage of larger dimensions in securing a vertical descent has been always recog- nized. At the Western Jumna canal rectangular linings were adopted with advantage. At the Solani aqueduct hol- low cubical stones were used at the beginning, and at Danowri oblong or square linings, thirty feet long and twenty feet deep, and subdivided into three or four com- partments, were used. When the structure of soft soil is too thin for the foundations to be placed below it, the soil must be consolidated; or the area of the foundation must be sufficiently extended to enable the ground to support the load. The ground may be consolidated by wooden piles; but in soils where they are liable to decay, pil- lars of sand, or mortar, or concrete,  rammed into holes previously bored, may be used. Artificial foundations are also formed by placing on the soft ground either a timber framework, surrounded occasionally by a burlap, or a mass of rubble stone, or a layer of sand, or a thick layer of fine sand spread in layers eight to ten inches thick, which, owing to its semisolidity, equalizes the pressure. A remarkable example of this method was afforded in the renovation, in 1844, of the arches over the bridge at Charleville-gate, at Charlevièr, where the old pile-work foundations had twice given way. A trench was dug 34 feet deep and 34 feet wider than the construction on each side, and inclosed by little walls. Into this cavity was thrown a mixture of sand, moderately wetted, then a layer of concrete, twenty inches thick, and upon this the masonry was built, which has stood perfectly. When the bottom of the excavation is silty, it is advisable to throw a thick layer of sand over it before driving piles, as the sand gives consistency to the silt. 16  17 A heavy superstructure is partially supported on a soft foundation by the upward pressure due to the depth below the surface to which it is carried, in the same manner that a solid float in a liquid when it displaces a volume of water equivalent to its own weight. Accord- ing to Rankine's building will be supported when the pressure at its base is $wA(1-\sin\phi)^{3}$ per unit of area, where $A$ is the depth of the foundation, $w$ the weight of the structure, $\phi$ the angle of volume, and $\phi$ the angle of friction. Mr. McAlpine, M. Inst. C.E., in build- ing a high wall at Albany, U.S.A., suc- ceeded in safely loading a wet clay soil with two tons on the square foot, but with a settlement depending on the depth of excavation. In order to prevent a great influx of water, and consequent softening of the soil, he sur- rounded the excavation with a paddle trench, ten feet high and four feet wide, and he also spread a layer of course gravel on the bottom.  18 When the foundation is not homogeneous it is necessary to provide against unequal settlement, either by increasing the bearing surface where the ground is soft, or by carrying an arch over the worst portions. HYDRAULIC FOUNDATIONS. Under this head are comprised all foundations in rivers, and where running water has to be contended with. Foundations are laid upon the natural surface of the ground, or on beds of gravel, sand, or stiff clay secured against scour by aprons, sheeting, rubble stones, or other means of protection. When the foundations are to be pumped dry, dams are resorted to if the depth of water is less than ten feet, and are usually utilised in the construction of bridges, where the water is less deep and rapid and the bank forms one side of the dam. The dam can be made of clay, or even earth free from stones and roots, with slopes of 1 to 1; the width at the top being about equal to the  19 depth of water when the depth does not exceed three feet in a current, or ten feet in still water. The leakage of a dam and the danger of breaches increase rapidly in proportion to the head of water. At Holland's Ditch, the great dam of sand, which was built by the city fascines, had to keep out a head of water of twenty-three feet at high tides from the foundations. M. de la Gournerie constructed a temporary dam of silt, 4,400 feet long, at St. Nasaire, in 1841, and a permanent dam at the existing dock. The dam was thirteen feet high, four feet wide at the top, with a pitched slope of 1 in 3 towards the sea, and an inner slope of 1 in 5. Concrete makes a solid dam, but it is expensive to construct and difficult to re-move. A masonry dam 328 feet long was built at Lorient in 1867. A cofferdam with a double row of piles takes up less space and is less liable to be worn away or breached than an earth-work dam. At the Assay viaduct a dam was made of two rows of piles, with  20 boards filling up the spaces between the piles, the center of the dam being filled with well-panned silt, and protected out-side with rubble stones. It supported the pressure of a head of water of from five to six feet, and cost £1 1s. 6d. per linear foot, or £1 0s. 10d. per linear foot. The width of a cofferdam is often as great as the head of water; but if the cofferdam is strutted inside, so that the clay merely acts as a watertight lining, the width need not exceed one-third of the head. In a cofferdam of concrete at Marseille constructed for the basin of the graving docks, the widths were calculated at 0.45 of the total height, the maximum width has thus attained twenty feet. In building the harbour of Lorient, on a foundation dry at low water, a single row of strutted piles, 34 feet apart, planked from top to bottom on both sides, was used (Fig. 6), and the space between the planking, ten inches wide, was filled with silt pressed down. When the filling is so much reduced in thickness the planks are carefully joined, and the  21 Fig. 6. LORIENT clay is mixed with moss or tow, or some times with fine gravel or pounded chalk. As water leaks through joints and concavities, they are packed as high up as possible, and the bottom is packed out or cleaned before the clay is put in. When the sides of the part to be enclosed are sufficiently close they may be effectively supported by a series of stays, as was done in making the dam for the con-  22 struction of the apron of the Melun dam (Fig. 7), where struts were put in at intervals of 164 feet. **Fig. 7.** A diagram showing the construction of a cofferdam. The cofferdam is circular with a diameter of 325 feet. It is constructed with piles being one foot square and fifty feet long, with walings attached. **MELUN** The Grimsby Dock works, and the Thames Embankment works, furnished examples of cofferdams constructed to bear the pressure of a great head of water. For constructing the Zuider Zee locks on the Amsterdam Canal a circular dam, 325 feet in diameter, was erected, consisting of three rows of piles, the first row being, the piles being one foot square and fifty feet long, with walings attached. Eventually, in consequence of accident, a third row was added, and the dam fur- ther strengthened by sloping banks of sand on both sides, the outer slope being protected by clay and fascia work. The head of water against the dam was occa- sionally twenty feet.  23 If large springs burst out in an exca- vation they must be either stopped up with clay or cement, or be confined with- in a wooden, brick, or iron pipe in which the water rises till the pressure is equal- ised, and then it is allowed to escape as soon as the masonry is sufficiently advanced and thoroughly set. If, however, there is a general leakage over the whole bottom of the excavation it must be stopped by a layer of concrete, incorporated with the foundation courses (Fig. 8). Fig. 8. Cofferdams or troughs of concrete had been used on a large scale at Toulon and Algiers for the construction of repairing docks. Where there is not space for a clay dam, timber sheeting well struttled and  24 caulked is used. For instance at the Custom-house quay of Rio de Janeiro a dam of square sheet piling, with counterforts of cross sheet piling, and made wateright by hoop iron let into grooves in each pile, served to support the pres- sure of about 300 tons per foot of water. A similar structure, however, at the West India Docks was floated away by an equinoctial spring tide, owing to the want of tenacity of the ground. When the head of the tide was under five feet, water enough is sufficient to keep up the canvas being weighted at the bot- tom, and nailed to a beam at the top. It is in every instance advisable to take out the earthwork for foundations in lengths. In the construction of the Victoria Docks a metallic othardum was used, which was very easily displaced by float- ing. Hollow timber frames without a bot- tom, and made wateright at the bottom after being lowered by concrete or clay, are suitable in water from six to twenty feet deep on rocky bed, or where there  25 is only a slight layer of silt. This meth- od was resorted to by M. Beaudemoulin, between 1857 and 1861, at the St. Michael, Soferino, Change and Louis Philippe bridges at Paris. The timber frame at the St. Michael bridge was fif- teen feet wide, and fifteen feet high; and nineteen feet eight inches wide at the base, with a batter of 1 in 5; the up- rights were six inches square, and 6 feet apart; the framework was made of oak, and the planks of deal (nine inches by three inches) were laid on the frame, being covered by small laths nailed on to the planks. Fourteen crabs placed on four boats supported the framing, and let it down as it was built up; this was weighted with stones to sink it on the foundations prepared by digging, and its weight kept it in place between the wallings and beaten down lightly. A toe of rubble stone outside supported the pressure of the concrete inside. The whole operation took ten days, and in one month the masonry was finished up to the plinth. The caissons, including erection, cost £300.

is only a slight layer of silt. This meth-

od was resorted to by M. Beaudemoulin,

between 1857 and 1861, at the St.

Michael, Soferino, Change and Louis

Philippe bridges at Paris. The timber

frame at the St. Michael bridge was fif-

teen feet wide, and fifteen feet high;

and nineteen feet eight inches wide at

the base, with a batter of 1 in 5; the up-

rights were six inches square, and 6 feet

apart; the framework was made of oak,

and the planks of deal (nine inches by

three inches) were laid on the frame,

being covered by small laths nailed on

to the planks. Fourteen crabs placed on

four boats supported the framing, and let

it down as it was built up; this was

weighted with stones to sink it on

the foundations prepared by digging,

and its weight kept it in place between

the wallings and beaten down lightly.

A toe of rubble stone outside supported

the pressure of the concrete inside. The

whole operation took ten days, and in

one month the masonry was finished up

to the plinth. The caissons, including

erection, cost £300.

 26 The caissons of the bridges at Vienna, sunk twelve feet below water level, cost £2 18s. 6d. per linear yard of circumfer- ence. At the Point-du-Jour viaduct the caissons were 131 feet long, and from twenty-six to twenty-eight feet wide, from twenty-one to twenty-six feet high. The long sides were put together flat on the ground, and were lifted up to allow of the short sides being fixed to them. A few hours sufficed for depositing the caissons in its place. M. Pissard built structures at Besançon after the war of 1870, used caissons in two por- tions, as the lower portion had to re- main, whilst the upper portion was only needed for a time. Some nails and straps fastened the two parts together. A layer of clay was placed under the rubble toe outside them, to prevent leakage between the concrete and the planks. This expedient was first adopted by M. Desnoyers, in order to pump dry the foundation which he carried down into the clay, so as to build masonry walls on the bottom without using concrete. At  27 the Anline viaduct in Brittany, MM. Demoyers and Arnoux made a caisson seventy-five feet six inches by thirty-four feet nine inches, and nearly twenty-three feet high (Fig. 9), and, with the excep- tion of the bottom portion, caulked be- forehand. When it was deposited the bottom planks were slid down between the lower set of walings, and a toe of puddled clay "A," protected from the rush of the current by canvas, was put round the bottom outside. The caisson was so watertight that a Letestu pump A diagram showing the construction of a caisson. The top part is labeled "Caisson" and shows the upper section of the caisson. Below it, there is a section labeled "Lower Set of Walings" showing the lower part of the caisson. At the bottom, there is a section labeled "Bottom Planks" showing the bottom portion of the caisson. Aulne  29 working two or three hours each day kept the foundations perfectly dry. When the caisson, put together on a stage supported on eight boats, was ready for depositing, the sluice doors of the Gulliver, via the sluice gates, were opened, allowing the caisson till the projecting pieces "B" touched the ground, and by cutting the beams fastening these projections to the boats, the boats were set free. As the tide rose the caisson floated, and the boats were attached to its upper part, which, being raised by means of a winch, allowed for the projecting pieces to be taken off. The depositing was completed by opening the sluices of the dam at high water, and as the water fell the caisson, weighted with rails, sank on the dredged bottom. The caisson, weighing one hundred and forty tons alone a mass weighing seventy-four tons was safely and accurately deposited. The cost of one caisson was £740; and the cost of the foundation below low water did not exceed £1 12s. 6d. per cubic yard. At Lowestoft large caissons, from twenty-three to twenty-four feet  high, were employed; but an interior dam of concrete forming a permanent part of the foundation was used instead of an external toe of clay. At Quimperle M. Dubreuil made the caisson watertight by a dam of clay inside, which necessitated a somewhat larger caisson, but admitted of the removal of the timber. When the river is sparsely populated, as on the large American rivers, a sort of double-cased crib-work dam is frequently adopted. M. Malézieux has given various details of this class of work, such as the cofferdam in Lake Michigan, and the water supply for Chicago. A caisson 200 feet long and 98 feet wide, enclosed by double watertight sides from thirteen to nineteen feet high, was used at Montréal on the St. Lawrence. The interval between the two sides was about eleven feet wide, and planks at the bottom so that the caisson could be floated into place. When the caisson was sunk, piles were driven in holes made in the bed of the river to keep it in place, and 29  30 the bottom was made waterlight by a lining at the sides of beams and clay. These kinds of caissons are only suitable where the bottom is carefully levelled. Although iron caissons are generally used for penetrating some distance into the soil, they are intended for iron caissons being merely deposited upon the natural bed. M. Pluëtty founded one of the large piers at Nogent-sur-Marne in a plate iron caisson, which weighed about seventy tons, and cost £ 8,600, with base and superstructure, and thick, and protected by rubble stone. Its dimensions at the bottom were seventy-two feet by 37 feet, with rounded corners and a batter of 1 in 5, 294 feet high, including a length of five feet, which could be removed when the work was finished. The thickness of the plates was from 3 inch to 4 inch, and it was struttred inside with timber. The same system was adopted at Brême, where caissons sixty-nine feet by 164 feet were used for the four ordinary piers, and the width increased to 424  31 feet for the pier on which the bridge turns; their height was 11 feet, and the thickness of the plates 8 inch. The operation of sinking the caissons from a floating stage occupied about seven hours. A layer of concrete nine feet thick was placed on the bottom and left for twelve weeks to set before the water was pumped out. The methods employed for laying foundations in the water, either on the natural surface or after a slight amount of dredging, have been described. A rubble mound foundation is sometimes employed for dams where any settlement can be repaired by adding fresh material on the top; also for landing-piers in lakes by solidifying the upper part with concrete, and in breakwaters where a massive superstructure is erected on the top. Such a method, however, is not suitable where a slight settlement would be injurious; and in the sea the base of the mound is generally less exposed to scour than in a river.  32 Another method consists in sinking a framing, not made watertight, inside which concrete is run, and the framing remains as a protection for the concrete, and is surrounded by a toe of rubble. If the framing is of some depth iron tie- rods are driven into the ground to support the bottom, and when the bottom has been dredged, to enable the framing to support the pressure of the concrete. When piles can be driven the framing is fixed to them. The piles, five to eight feet apart, have a double row of holes bored through them at right angles to each other, in which close planking is driven, from ten to fourteen inches wide, and from three to five inches thick, and sometimes, when the scour of a sandy subsoil has to be prevented, the planks are grooved and tongued, or have projecting pieces put on their ends, and are driven into the panels. The inefficiency of a simple framing of planks for foundations on running sand was demonstrated by the destruction of the Arroux bridge at Digoin, and the Gue-Monsault bridge over the Somme by the flood of Septem-  83 ber 1866, in spite of the fascines and rubble stones protecting their piers, owing to the washing out of the underlying sand through the intense action of the rapid whirling currents. The cost per superficial yard of a casing formed with piles and planks is about £1, including the cost of driving 46 feet. Open framing is sometimes used for enclosing a mound of rubble stone. These mounds require examination after floods, and renewing them, the mound has become perfectly stable. In permeable soils foundations of concrete enclosed in frames are frequently employed, as, for instance, for the foundations of the bridges at Jena, Austerlitz, and Alma bridges at Paris ; but in siltly and watertight soils founda- tions in excavations pumped dry are preferable. The bed of the Rhone at Tarascon, consisting of sand and gravel, in which piles are difficult to drive, is subject to scour in floods to a depth of 46 feet. Foundations, however, were laid there,  34 at considerable expense, by frames with double linings, ten feet apart, in which large blocks were placed with unknown stones on them; the ground was then dredged inside the frame to twenty-eight feet below low-water level, and 260 cubic yards of sand were deposited in twenty-four hours. Lastly, concrete can be deposited *in situ* for bridge foundations; and though concrete blocks are only used in sea works, bags of concrete, like those at Aberdeen, by Mr. W. M. Jones, C.E., might be sometimes employed, instead of rubble stones, for forming the base of piles or for preventing scour. Piles are used where a considerable thickness of soft ground overlies a firm stratum, but when the stratum has insufficient consistency to afford a lateral support to the piles, otherwise masonry piers must be adopted. The piles are usually placed from $\frac{2}{3}$ to $5$ feet apart, center to center, and the distance is occasionally increased to $4\frac{1}{2}$ feet for quays or other works only slightly.  35 LIBRARY OF THE UNIVERSITY OF CALIFORNIA ly loaded. Sometimes under abutments or retaining walls the piles are driven obliquely to follow the line of thrust. The Libourne bridge rests on piles 24 feet apart, and driven about forty feet in sand and silt, on the Voulzie viaduct, on the Paris and Montparnasse lines. Some piles were driven eighty feet without reaching solid ground, and the ground between the piles had to be dredged, and replaced by a thick layer of concrete. Piles which have not reached firm ground sustain considerable pressure from the lateral friction, as for instance, in the soft clay at La Rochelle and Rochefort piles can support 164 lbs. per square foot of lateral contact, and 128 lbs. in the silt at Lorient. On the Cornwall railway, viaducts were built upon piles, sixty-five to eighty feet apart, with a group of four fastened close together, by a four- ton monkey with a small fall. A timber grating is fastened to the top of the piles, or a layer of concrete is deposited, as at Dirschau, Hollandseep, and Dordrecht; or both grading and concrete, LIBRARY OF THE UNIVERSITY OF CALIFORNIA  36 as the grating distributes the load and strengthens the piles. Planking is sometimes put on the framing which distributes the pressure, as at London Bridge, but it is considered objectionable as it prevents any connection between the superstructure and the concrete, and increases the amount of space between the piles from the river bed to low water is sometimes filled with rubble stones, and sometimes with concrete (Fig. 10), which is less liable to Fig. 10. disturbance. When the ground is very soft a filling of clay has been preferred on account of its being lighter than concrete.  37 A mixed system of piling and water-tight caissons, of rubble filling and concrete, was adopted at the Vernon bridge. After the piles had been driven the spaces between them were filled up to half their height with rubble stones: a caisson ten feet high was then placed on the top, and a bottom layer of concrete deposited in it. In a month's time the interior of the caisson was pumped dry, the heads of the piles cut off, and the filling worked into concrete completely to water level. The caisson was cut off to the level of the grating as soon as the pier was well above water. The foundation cost altogether £14 8s. per square yard of base of the pile. The heavy ram of Namymth moved by steam, with a small fall, but giving sixty to eighty blows per minute, enabled piles to be driven thirty-three feet in a few minutes, and with much less chance of divergence or jumping than in driving with less powerful engines. In certain soils, in which there is a momentary re-  38 istance during pile-driving, it has been proposed to bore holes in which the pile should be afterwards driven. At St. Louis the annular piles, 4 feet in diameter, made of eight pieces of wood, each weighing about 1000 pounds, were driven by the aid of the hydraulic sand-pump working inside, the invention of Mr. Eade, M. Inst., C.E. The load that a pile driven home and secure from lateral flexion can bear may be estimated at from one-eighth to eight-ninths of the weight, which varies between 5,700 and 6,500 lbs. per square inch. Thus, taking a fair load of 710 lbs. per square inch, a small pile of seven inches diameter will bear about twelve tons, and a pile of eight inches diameter will bear about sixteen tons; and a pile to bear the head of twenty-five tons used as a unit by M. Perretot should be about ten inches in diameter. According to M. Perretot a pile can support a load of twenty-five tons as soon as it refuses to move more than $\frac{1}{3}$ inch under thirty blows of a monkey, weighting  30 eleven cwt's ninety lbs., falling four feet or under ten blows of the same monkey falling twelve feet. At Nantilly, how-ever, M. Perronet placed a load of fifty-one tons on piles thirteen inches square, but driving the pile till it refused to move more than $\frac{1}{4}$ inch under twenty-five blows; and at Bordeaux the same weight falling forty feet; but such a load is unusual. At Bordeaux the driving was stopped when the pile did not go down more than $\frac{1}{4}$ inch under ten blows of a monkey, weighing 1,000 lbs., falling about fifteen feet; but all of the piles stood considerably below the load; a pile being twenty-two tons; whereas at Rouen, by insisting on M. Perronet's rule, no settlement occurred. From experiments made at the Orleans viaduct, M. Sallier concluded that piles might be driven with security a load of forty tons when they refuse to move more than $\frac{1}{4}$ inch under ten blows of a monkey weighing fifteen cwt's, and falling about thirteen feet. Various formulae have been framed for  40 calculating the safe load on piles, which are quoted in a paper by Mr. McAlpine, M. Inst. C.E., on "The Supporting Power of Piles," and in a Paper on "The Dordrecht Railway Bridge," by Sir John Allemey, Bart., M. Inst. C.E. Mr. Wether- bach's formula, as given to Mr. McAlpine's rule it appears that, seeming a safe load, the limiting size of the pile might be 34 inches instead of 4 inches for ten blow; and the formula shows that large monkeys should be adopted in prefer- ence to a small one, but this is agreeable with practice for preventing injury to the piles. In order to provide against the danger of overturning in silty ground, the ground is sometimes first compressed by loading it with ballast; but, when it is cut away after a few months those places where foundations are to be built. At the Oost bridge it was even necessary to connect the piers and abutments by a wooden apron, which, for additional security, was surrounded by concrete (Fig. 11). The abutment was made  41 Fig. 11. A section of the viaduct showing the method of filling up the hollow to lighten it, and the embankment, "R," had compressed the silty ground to m.m. The foundations cost £23 1s. 6d. per superficial yard for depth of fill, and £10 15s. 6d. per yard three feet from the natural surface to the top, or £1 16s. 10d. per cubic yard, a high price due to the difficulties met with and the bad weather. At the bridge of Bouchemaine, near Angers, the bending of the piles, which traverse about twenty feet of soft clay, was caused by filling them with great masses of rubble stones. Occasionally foundations on piles have failed or suffered great sets or lateral  42 displacements. At the Tours bridge, many arches have fallen at successive times; holes in the foundations had to be refilled with lime, and below certain arches a general bed of concrete was afterwards established. Founding piles require a bottom carefully levelled, on which to be lowered. Labelye, in 1750, deposited the caissons of old Westminster bridge on the dredged bottom of the river; but usually this kind of caisson is deposited on piles cut out of the river bottom. Caissons have oak bottoms and movable sides of fir, and enable the masonry piers built inside to be lowered on piles previously driven. The oak bottom serves as a platform for the pier, and the movable fir side can be raised against each caisson. At Iver, with only two sets of movable sides, the contractor was able to put four caissons in place in one month. The bottom, which consists of a single or double platform, has timbers projecting underneath which fit on to the rows of piles. The movable sides  43 are sometimes made in panels, which fit into grooves both in the bottom framing and in upright posts, placed about ten feet apart, which are tenoned at the bottom, and kept in place at the top by transverse bolts, called caissons. The different parts of the sides are tightly pressed together by the bolt, A B (Fig. 12). In other instances, as at the bridge Fig. 12. of Val Benoit over the Meuse, the sides butt against the vertical sides of the bottom, against which they are pressed by keyed bolts, D, placed at intervals of five feet (Fig. 19). The caisson is kept near the shore whilst the first courses of masonry are being built in it; it is then, SEVERAL LINES OF TEXT AND NUMBERS  44 on a favorable opportunity, floated over the site of the pier prepared to receive it, and is gradually sunk by letting in water. At the Bordeaux bridge the caissons had a height of twenty-six feet, and were divided into spaces three feet wide. This work, which comprises seventeen arches, was founded in a great depth of water, about the year 1870, by the engineers Deschamps and Billandel. A diagram showing a vertical section of a caisson with a horizontal cross-section at the top. Fig. 13. A diagram showing a vertical section of a caisson with a horizontal cross-section at the top. Fig. 14. VAL BENOIT In sea works the laying of foundations in the water is managed differently. Thus artificial blocks of concrete may be deposited by the help of divers, as at  45 Dover pier; or much larger masses may be moved by powerful machinery, as, for instance, blocks of 150 to 200 tons put down at Brest in 1868, and at Dublin by Mr. Storey, M. Inst. C.E. For small landing piers, and for piers of bridges in rivers not exposed to the breaking up of ice, artificial blocks of metallic frames work most satisfactorily under water on the top of timber piles cut off level, a plan adopted by Mr. Maynard, M. Inst. C.E., on a foundation of screw piles. Screw piles were introduced by Mr. Mitchell, M. Inst. C.E., for securing buoys, and for making it of advantage to the construction of bollards and beacons, on account of the resistance they offer to drawing out; but as in the process of screwing down the ground is more or less loosened, judgment must be used in employing them for mooring or warping purposes. In founding buoys or beacons they should be screwed down from fifteen to twenty feet below the level to which the shifting sand is liable to be lowered. Even when all cohesion  46 of the ground is destroyed by screwing down a pile, a conical mass, with its apex at the bottom of the pile and its base at the surface, would have to be lifted to draw the pile out. The resistance to settlement is also increased by the bearing surface of the screw; and the screw pile is accordingly to be pre- ferred to ordinary piles, when the soil is of indefinite depth, because when the shocks produced by ordinary pile-driving are liable to produce a disturbance. The screw pile has likewise the advantage of being easily taken up. Screw pile haws been principally used in England and in the United States. They have usually one or two spirals pro- jecting considerably from the shaft; these spirals being cylindrical for soft ground and conical for hard ground, and either of wrought iron or of cast iron. The shaft may be made of wrought iron or of cast iron, which must be pointed at the end for hard ground, but cylindrical and hollow when the ground is soft. The screw will penetrate most soils except  47 hard rock; it can get a short way into compact marl through loose pebbles and stones, and even enter coral reefs. A screw pile was driven by eight capstan bars, twenty feet long each, by four or five men, with a screw four feet in diameter, passed in less than two hours through a stratum of sand and clay more than twenty feet thick, the surface of which was about twenty feet below water, and dug down to the bed of shale one foot into an underlying schistous rock. At the Clevedon pier screw piles penetrated hard red clay to depths varying between seven and seventeen feet, and although the screw had a pitch of five inches, the thread was only one more than three inches in one turn. Mr. W. Lloyd, M. Inst. C.E., has recorded an unsuccessful use of screw piles, which in the shifting sandy bed of a South American river, were called "corkscrew," and were overturned in the first breaking up of the ice. At Hamburg screw piles, in sets of three and joined at the top, are used as bollards.  48 The piles are hollow wrought-iron tubes, 4 inch thick, furnished with a screw both inside and outside, 30 feet long, which is one foot (Fig. 14). To screw them down two capstans were used to pull the two ends of a rope wound round the head of the pile, the force transmitted to the pile being thirty times that applied at an arm of the capstan, and towards the close, when the pile was nearly sunk, nearly thirteen feet, seven men were required to work each capstan. At the commencement each turn of the screw produced a descent of ten inches, and hardly nine inches at the end. A vessel struck, and against one of these bolards, and broke off the top without shifting the piles. Piles with dies, used in the first instance at the Leven and Kent viaducts, by Mr. Brunel's, M. Inst. C.E., differ little from those described above, except in their method of sinking them. This operation was performed by sending a jet of water down a wrought-iron tube inside the cast-iron pile, which washed away  49 the silty sand from underneath the disc and caused the pile to descend. The sinking cost about 3s. 6d. per linear foot, whereas at Southport pier, where water was obtained from the waterworks, and ten piles were sunk per tide, the sinking only cost 4d. per linear foot. Wooden piles, with a cast-iron shoe carrying a disc, might easily be sunk in the same manner, the water being brought carried eccentrically through the disc. Hollow wrought-iron piles have also been forced down by blows of a monkey, in silty and sandy ground interpersed with boulders, to a depth of about forty feet; the diameter of the pile being about one-inch inch, and the diameter 18 inches. On the Cambrian railway, Mr. Coneybear, M. Inst. C.E., drove wooden piles down below the surface, by means of a lengthening piece of cast iron on the top of the piece of wood or lead being interposed between the monkey and the cast iron. Large masonry piers carried through thick layers of soft ground to a solid bed  50 may be constructed by various methods, and constitute the best kind of foundation in such a situation. The method of caused wells is suitable where the soil is sufficiently compact and watertight to admit of pumping the water dry, and where the depth of water is small and can be kept up by cofferdam or a caisson, without a bottom. The well is sunk by the ordinary methods of sinking wells or driving headings in silty ground. At the Auroy viaduct, a muddy stratum, twenty-six feet thick, was got through by this method. In building the viaduct at Saint-Georges over the Vilaine, in Brittany, resting on six pillars carried down fifty feet below the water-level, the same method was adopted; but for the lower portion of the excavation a smaller framing had to be sunk instead of driven. This requires about twenty days for the excavation, and twelve days for building the masonry. The cost is from £2 16s. 10d. to £2 9s. per cubic yard of foundation complete. When the pier is so wide as  51 to render the strutting difficult, an outer ring can be first lowered, which serves afterwards as a casing for excavating the inner portion. Where permeable gravel or very liquid silt has to be traversed it is necessary to resort to tubular foundations. Cylindrical foundations are sunk with or without the aid of compressed air according to circumstances. These foundations possess the two great advantages of being capable of being sunk to a considerable depth, and of presenting the least obstruction to the current. In a well-constructed case acts as a movable cofferdam, which is sunk by being weighted, and enables the foundations inside to be built up easily and cheaply. This method was first adopted by Mr. Redman, M. Inst. C. E., at Gravesend, and has been used at Charing Cross and Cannon Street bridges; and also for the piers of the Victoria bridge over the Thames. Iron cylinders are preferred in certain cases to cylinders of brick, masonry, or concrete, on  52 account of the ease with which they are lowered in deep water on to the river bed; in spite of the disadvantages attaching to them of high price, of the considerable weights required for sinking them, and lastly, of being only cases for the actual pier. In 1823, Sir Mark Brunel, in sinking the wells of access to the Thames Tunnel used linings of brickwork, 50 feet in diameter, and resting on iron frames with vertical tie-rods. At Rochester, M. Guille- main used linings of masonry resting on plate-iron rings and strengthened by iron chains. The lining was sometimes 10 feet, sometimes 13 feet in diameter, and it was found that the facility and rate of descent of the larger linings more than compensated for the additional material. At Lorient the Cauban foot- bridges were made of cast-iron tabular frames, sunk from 50 to 60 feet below high water. When the ground is very soft it has a tendency to run into these tabular cofferdams when the water is pumped out.  53 The method of sinking wells in India has been previously referred to. Mr. Imrie Bell, M. Inst. C.E., added a pole to the jham used by the natives to save the trouble of diving, but even with this addition the process was slow. The foundations of the Sydney viaduct, on the Darling Harbour, were sunk by this method. In more recent works the curb was made of iron instead of wood, and angular as in the case of the Jumna bridge. The first lengths were short, 5 or 6 feet long, and the verticals between lengths of 10 feet, and afterwards lengths of 13 and 16 feet were added. At the Glasgow bridge the lining was of cast-iron rings, being easier to lower in mid-stream; but for the quays and docks on the Clyde linings of brickwork and concrete were adopted, which are cheaper in economy. Mr. Milroy, Assoc. Inst. C.E., considers that with concrete, which can be moulded at an edge to the bottom, all metal additions may be omitted where only silk or sand have to be traversed, and that the bottom ring should be of  54 iron for penetrating harder soils. In the Clyde extension works the walls were filled up with concrete, and a double row of cylinders of 9 feet diameter were adopted in preference to a single row of 12 feet. It would be possible in this arrange- ment to fill the spaces between the adjacent cylinders and form them into a solid mass by filling up these inter- stices with concrete. Mr. Ransome used cylinders of "amphite" for the Harmitage wharf on the Thames. The Dutch piers have often been used oval-shaped iron tubes sunk by dredging inside. Thus in the bridge on the North Sea Canal the piers are elliptical; the one on which the opening portion turns having axes of 236 and 18 feet, and the others axes of 236 and 14 feet. The horizontal flanges at right angles to the axis of rotation are so short that the radius of curvature is increased, and the vertical ribs are not continuous, but ar- ranged so as to overlap. The bridge over the Yssel, on the Utrecht and Co- logne railway, rests upon cylinders which were sunk by internal dredging 17½ feet below the river bed.  55 LIBRARY OF THE UNIVERSITY OF CALIFORNIA In France sinking cylindrical cylinders was a common practice, but sink- ing is not often resorted to in rivers, pos- sibly owing to a failure of this system at Perpignan, where the sinking of a maasonry cylinder by dredging was stop- ped by boulders, and compressed air had to be used. Moreover, the foundations of bridges at Rivière-Sainte over the Saône at Lyons, and the jetty made at Havre in 1861, were executed by this method. For the walls of the wet dock of Bordeaux rectangular wells have also been sunk by this process. The extension of the system must depend chiefly on improvements in the dredging machinery, of which the suc- cessive steps in advance already attained may be noted. The plan was suspended by Kennard's and pumped. With this machine a well, 124 feet in diameter, was sunk in the Jumma 8 to 10 inches per hour by four- teen workmen. As the Kennard pump was not able to work in the compact clays and conglomerate met with in rebuilding the bridges over the Beas and the Sulej  56 Bell's dredger was adopted, which consists of a semi-cylindrical case with jaws opening in two quadrants, like the American dredger of Morris and Cummings. Mr. Stone, M. Inst. C.E., however, mentions that when it met with a hard stratum at a depth of 3 feet 10 inches was accomplished in three months, whereas in the upper layer the progress was much more rapid than with the sand-pump. Next came Mr. Milroy's 'excavator,' consisting of an octagonal frame from which are suspended eight triangular spades. These spades are forced vertically into the ground and are then lifted by chains so as to come together and inclose the earth, which can then be raised and discharged. At the Glasgow bridge the progress was, on an average, 1½ feet per day, and the maximum 20 feet. At Plantation Quay the average for a cylinder was about 4 feet per day, but these cylinders were impeded in their sinking by tongues and grooves, so that double this rate  57 might be reckoned on for unconnected cylinders. Another machine is the "screw pan" used at the Loch Ken viaduct, a conical perforated vessel, the diameter at the top being 3 feet, and furnished at the bottom with a screw which draws out the sand and mud. The sand and mud entering the vessel are retained by little leather valves when the instrument is lifted. It works well in silt and clay; in harder soils a smaller vessel is needed. Lastly, there is the "boring head" used by Mr. Bradford Leslie, M. Inst. C.E., at the Gorai bridge. A revolving plane with blades underneath, able to disintegrate hard clays and compact sand, is worked inside the cylinder, and at the same time the canal of water is drawn up and removed from the cylinder by a siphon. To maintain an upward pressure in the siphon the level of the water in the cylinder is always kept higher than b. the river. The boring-head made one revolution in about one minute and a half or two minutes, and  58 excavated through clayey and sandy silt at a rate of about 1 foot per hour. One advantage possessed by this system is that the rate of progress is independent of the depth. The side piers of the Gorai bridge are 30 feet deep below the surface and the river pier is 98 feet below low-water level. The only bridge the foundations of which have been carried down as deep as those of the Gorai bridge is the St. Louis bridge over the Mississippi; but this method of compression, though it has overcome the difficulty and loss of life attending it, would have been impracticable with coolie labor at Gorai. The system of sinking by dredging is generally to be preferred to the compressed air system, except where numerous obstacles, such as boulders or embedded trees, are met with. The friction between cylinders and the soil depends on the nature of the soil and the depth of sinking. For cast iron sliding through gravel the coefficient of friction is between 3 and 3 tons  59 on the square yard for small depths, and reaches 4 or 5 tons where the depth is between 20 and 30 feet. In certain ad- hesive soils it would be more. In sinking the brick and concrete cylinders in the silt of the Clyde it was found to amount to about 24 tons per cubic yard. Passing on to the consideration of the pneumatic systems, the process of Dr. Potts was one of the first employed for sinking tubular foundations by the help of air. The cylinder in process of being sunk was connected with a pipe in which a vacuum was produced, and a communication between them being sud- denly made a shock was produced by the rush of air. By this means Mr. Cowper, M. Inst. C.E., succeeded in driving down cylinders four feet at a time, thus get- ping over the system of using air for applying a downward pressure on the cylinder, as dredging had still to be re- sorted to for removing the earth from the inside, and, moreover, there was a considerable influx of the surrounding soil, and frequent divergencies from the  60 perpendicular. Mr. Bramwell, M. Inst. C.E., observing the effects produced by the rush of air out of the cylinder, in an adjacent mine, suggested the making of a watering from the interior of the cylin- der towards its external surface, a pro- cess which would disintegrate the earth lubricate the sliding cylinder, and pre- vent the influx of the soil. The dif- culties of the Potts process increase with the size of the cylinders, and when, after the cylinders, 10 feet in diameter, of the Shannon bridge it was abandoned after an unsuccessful attempt. The method of compressed air for enabling operations to be conducted under water was first mooted at Chalon, the diving-bell; but the application of it to a cylinder forced down by undermining was first made, in 1839, at Chalon for working a coal seam rendered inac- cessible by the infiltrations of the Loire. After having undermined a space 15 feet square, and driven down a cylindrical lining of sheet iron, 3 ft feet in diameter, it occurred to the engineer, M. Triger, to cover over the  61 top of the cylinder, and by forcing air in to drive out the water and admit the workmen. An air chamber was formed at the top with double doors, serving as a sort of look for the passage in and out of the cylinder of men and materials without giving an outlet to the compressed air, which would fill up the cylinder carried off the water from the bottom. In 1848 M. Triger sank another cylinder, 6 feet in diameter, in the same way, and suggested the employment of the method for the foundations of bridges. The first bridge foundations of this kind were carried out, in the years 1851–52, at the Rochester bridge on the Med- way, which has masonry piers each sup- ported on fourteen cylinders, 6 feet 11 inches in diameter, 30 feet deep in water. Having begun with the Potts process till on alighting on old foundations it proved useless, Mr. Hughes, M. Inst. C.E., con- ceived the notion of reversing the cur- rent of air, and sinking the cylinders by the help of compressed air. The success  82 of this method recalled to mind earlier suggestions in the same direction, such as the patent of Lord Cochrane, in 1880, for excavating foundations by compressed air, and that of Sir W. M. Collingwood, in 1876, to Sir M. Brunel to try to stop the rush of water into the Thames Tunnel by forcing in air. At the Chepstow bridge foundations the late Mr. I. K. Brunel, Vice-President first C.E., abandoned the Potts process on coming to the conclusion that it could resorted to compressed air, which he also subsequently employed in commending the foundations of the iron cofferdams used for the pier of the Saltash bridge. The various details of the compressed air system have been fully described in all of the works in which it has been employed. Theoretically, when the lower edge of the cylinder has reached a depth of $A$ feet below the surface of the water, the pressure required for driving the water out of the excavations is $\frac{5}{3}$ atmospheres; but frequently the intervention  63 of the ground between the bottom of the river and the excavation enables the work to be carried on at a less pressure, as Mr. Brunel did at Saultash. A considerably greater pressure would be re- quired if the water had to be forced from the bottom of the river bed below the river bed; but this is avoided by placing a pipe inside to convey away the water, and M. Triger has found that the lifting of the water was facilitated by the introduction of bubbles of air into the water. Pressures of 2 or even up to 3 atmos- pheres do not injure healthy and sober men, and suit best men of a lymphatic temperament, but prove injurious to men who are plethoric or have heart disease. It is advisable to avoid working in hot weather, and to keep down the hours of work more than four hours per day, or more than six weeks consecutively. At Harlem, New York, however, workmen have remained ten hours under a pressure of 50 feet, and even 80 feet of water. On the other hand, at St. Louis under a  64 pressure of little more than 3 atmospheres several men were paralyzed or died, and the period of work was gradually reduced from four hours to one hour. From experiments on animals M. Barat has shown that the pressure caused by a sudden removal of pressure is due to the escape of the excess of gas absorbed by the blood. Beyond 6 atmospheres any sudden return to the normal pressure is attended with danger; the usual rate of fall is 0.5 mm. per atmosphere. The cylinders subjected to pressure should be furnished with safety valves, pressure gauges, and alarm whistles, as explosions occasionally occur. Iron rings from 6 feet to 12 feet in diameter are cast in one piece, and a caustic soda washer is introduced at the joints between the rings; cylinders of larger diameter are cast in segments, and cylinders of smaller diameters than 6 feet are rarely used. The thickness is usually 14 inch, increased to 18 inch or 14 inch were exposed to blows, in coni-  65 cal joining lengths, and in the bottom length. When two cylinders have to be sunk close together it is best to sink them alternately, as they tend to come together when sunk at the same time. At Macon, where there was only an interval of 3 feet between two cylinders, the cylinder was forced suddenly as much as 6 feet when the other was forced down. Sometimes where cylinders of small diameter have to be used the excavations are extended beyond the cylinder at the bottom, and filled with concrete to form a conical pier; this plan was adopted at Harlem bridge, New York, and by the late Mr. Cubitt, Vice-President Inst. C.E., at the Blackfriars railway bridge. Another way of accomplishing the same object is by en- charging the lower part of the cylinder, and putting in a connecting conical length, as was done by Sir John Hawkshaw, Past-President Inst. C.E., at the Charing Cross and Cannon Street bridges.  86 The cylinders at Bordeaux were forced down by MM. Nepveu and Eiffel, in 1859-60, by strong beams of wrought iron, moved up or down by the pistons of four hydraulic presses having 11 feet length of stroke. For a thrust of 60 to 70 tons, the force could be applied at pleasure, and regulated according to circumstances. At Argenteuil, where cylinders 12 feet in diameter had to be sunk, the concreting mantle was carried on a wooden framework, with only a circular shaft in the center, 3 feet 7 inches in diameter, lined with wooden framing, and enlarged at the bottom to a conical shape by a sort of cage of enclined beams buttressing against the bottom of the shaft (fig. 18). The cylinders were sunk to 16 feet below the low-water level, through mud, sand, gravel, and clay, on to mortar or limestone, and four screw-jacks of 20 tons power supported the bottom ring by means of flat, iron straps. After the sinking was completed the chamber at the bottom was filled with cement concrete, poured  67 around iron pipes placed near the sides so as to maintain the pressure of air during the operation. When this layer of concrete was set the pipes were closed with cement, the normal pressure re- stored by a shallow layer of wet con- crete. Concrete deposited under com- pressed air appears to set quicker, and to increase somewhat in strength, provided it is deposited in thin layers allowing the ex- cess of water to escape. At Saguenay this method was used on very dry bricks with the concrete. At Perpignan the foundations of a bridge over the Tet had been commenced by sinking a Masonry cylinder by dredging inside, but large stones being unexpec- tedly met with the method of compressed air had to be used. The 30-inch concre- tyler, 34 feet thick and 15 feet out- side diameter, with a batter outwards of 1 in 100, was lined inside with neat cement, and was covered with a plate- iron top 4 inch thick. The sinking was assisted when necessary by letting out air; the depth attained was about 30  68 feet. The cylinder was filled with con- crete, which for the first 64 feet was de- posited under pressure. The success at- tending this experiment has led M. Bastertot to recommend the deliberate application of compressed air to masonry cylinders for depths of less than 35 feet below low water level by means of the use of such a cylinder 18 feet in diameter, sunk by this method 26 feet deep and filled in, at £240. The foundations of the piers of the Kehl bridge were accomplished by the engineers, Mr. H. G. and Mr. D. H. Vaugier by application of the prin- ciples of the compressed air process, the sinking of a pier by its own weight, the sinking by dredging, and the cofferdam system. As the bed of the Rhine at Kehl consists of large masses of gravel, liable to be disturbed to a depth of 45 feet below low water level, it was de- emed advisable to carry the foundations down about 70 feet below low water. For the two central piers the chamber of excavation was divided into three  69 caissons, the length of each being 18 feet 4 inches, the width of the foundation. For the piers forming the abutments for the swing bridges there were four caissons, each 28 feet long, the breadth of all three being 10 feet. The plate iron forming the caissons was $\frac{3}{4}$ inch thick at the top, and $\frac{5}{8}$ inch thick at the sides, and strengthened by flanges and gussets. The top was strengthened by double T beams for supporting the weight of the water in the caisson. There were three shafts to each caisson: two being air shafts, 24 feet in diameter, one being in use whilst the other was being lengthened or repaired; the other shaft in the center was oval, open at the top and divided into two compartments for storing water at the bottom, so that the water could rise it to the level of the river. In this shaft a vertical dredger with buckets was always working, and the laborers had only to dig, to regulate the work, and remove any obstacles. The screw-jacks controlling the rate of descent had a power of 15 tons, and were  70 in four pairs. The wooden framing serving as a cofferdam was erected above the chamber of excavation; it was useful at the commencement for getting below the water, but might subsequently have been dispensed with. It was also found by experience that the chambers were sufficiently divided in diameter than in several divisions, and doors of communication were accordingly made through the double partitions. The iron linings to the air shafts were removed before the shafts were filled with water, maintaing the dredger was at first made of iron, but afterwards of brick for the sake of economy. The sinking occupied sixty-eight days for one abutment, and thirty-two days for the other, giving a daily rate of 1 foot 1 inch and 1 foot 8 inches respectively. The sinking of the caissons for the intermediate piers took twenty to thirty days, which gives a daily rate of two feet 7½ inches (Fig. 18). For large works, where the load on the foundations is considerable, carrying  71 Fig's 15. A diagram showing a vertical section of a structure with a pipe or conduit running through it, connected to a horizontal pipe or conduit at the bottom. The structure appears to be part of a drainage system or a similar engineering project. A diagram showing a cross-section of a pipe or conduit running through the ground, with a scale indicating its depth. The scale shows that the pipe is approximately 3 feet deep. Kehl down the foundations to a hard bottom is much better than piling. The dredger used at Kehl cannot be regarded as uni- versally applicable. Some soils are not suitable for dredging, and in other cases  72 the small amount of excavation renders the addition of an extra shaft inexpe- dient, as for instance at Lorient. The chamber of excavation is almost invaria- bly made of plate iron, but, unlike those at Kehl, with the iron beams above the ceiling, instead of below, so that the fill- ing in may be effected by hand. The cutting edge is always strengthened by additional plates. At Lorient the thickness was $\frac{3}{2}$ inches, with several plates stepped back so as to form a sort of edge; thus, the bottom was 5 inches thick at the bottom, and 4 inches at the top, and the roof was curved a little to increase its strength. At Vichy the plates were about 4 inch thick. At La Voula, Hollandse Diep, and Lacerne, a sort of masonry filling was placed against the iron plates which kept in place by gussets, placed to afford resistance against the pressure of the earth. At St. Maurice wooden struts were substi- tuted for angle-iron flanges; and at Vichy struts were put in at the base of the caisson, and also half-way up to sup-  78 port the sides. In consequence of these modifications, the caisson at Lacroix (502 feet by 132 feet) weighed only 28 tons; the caisson at St. Maurice (392 feet by 144 feet) weighed 16 tons; whereas at Kiel (394 feet by 19 feet, weighed 34 tons; at Lorient (394 feet by 11½ feet) weighed 27½ tons; and at Riga (344 feet by 16 feet) weighed 45½ tons. The height of the chamber of excavation should be about 8 feet 10 inches. Frequently the cofferdam casing is of iron, but in some cases the newly-built masonry from friction; and the upper portion of the casing can be removed when the work is completed. In a sea bed, with a siltly bottom, special precautions must be taken against over- turning. Artificial weights, which are addi- ting to the depth of immersion, are added to the effects of the current. Some di- vergence from the perpendicular at Lo- rient was due partly to this cause, but partly also to the absence of supporting screw-jacks. At Lorient there were two air locks, each connected with two shafts.  74 in which balanced skips went up and down (Fig. 16). On the top of the bot- Fig. 16 tom caisson a casing of sheet iron, from 1/2 to 4 inch thick, and weighing about 15 tons, was erected in successive rings. At the Nantes bridges, built in 1883 by M. M. Gouin for the railway of Roche-sur-Yon, twenty-two caissons were erected, and the depth of the concrete foun-  78 LIBRARY OF CONGRESS UNIVERSITY OF MICHIGAN dations varied from 30 to 60 feet. The same firm were the contractors for the pneumatic foundations at Hollandseh Diep for three piers, two being carried about 80 feet below high-water level, and the other 65 feet. As the river bed was very soft down to 50 feet below high water-level, and as it might be apprehended, it was necessary to perform the first part of the sinking as rapidly as possible. The working chambers, and the lower 16 feet of the caisson, and the shafte for 23 feet in height, were constructed on masonry and masonry built on the horizontal projections of the chambers. Each caisson was then slid down an inclined plane to low-water mark, and at high water two boats fastened together removed them to their proper site, where they were deposited and ground down into the ground. The excavation, the building up of the masonry, and the addition of successive lengths to the caisson, were carried on simultaneously. As the earthwork was easily removed, the caissons sank at a  76 rate of from 14 feet to 34 feet per day. The first two piers were each completed in forty-five days from the launching of the caissons. The Americans have adopted the pneumatic system for some large works, and international interest has been shown in this method. St. Louis bridge the foundations were carried to a greater depth than had ever been previously attained; and at East River bridge compressed air was used in wooden caissons of large dimensions. The particulars of the work at St. Louis have been given by Mr. Francis Fox, M. Inst. C.E. The hydraulic sand pumping tube of Mr. Eads must only be recorded. The following details of the East River bridge are derived from the treatise of M. Malézieux, previously referred to. The Brooklyn pier is 100 feet deep, the New York pier 75 feet below high water. To provide against unequal sinking, owing to the variable nature of the soil, consisting of stiff clay mixed with blocks of trap rock, Mr. Roebling decided to place the bottom of  77 the piers upon a thick platform of timber which formed the roof of the working chamber (Fig. 17). The sides were also Fig. 17. made of wood, as being easier than iron to launch and deposit on the exact site. The roof consisted of five tiers of beams, 1 foot deep, of yellow pine, placed one above the other and crossed, the beams being tightly connected by long bolts. The working chamber was 167 feet by 108 feet, 3 feet high at the centre. The side walls had a V section, with a cast-iron edge covered with sheet iron; the walls had a batter inside outwards of 1 to 1, and 1 in 10 on the outside. Five transverse wooden partitions, 2 feet thick Diagram showing the interior of the working chamber.  78 at the bottom, served to regulate the sinking. When the caisson had been put in place, twelve tiers of beams were added on the roof of the chamber of the Brooklyn pier, and nineteen on that of the New York pier so that the water above waterline, the caisson could be built without a cofferdam lining. The excavation, to the extent of 19,600 cubic yards, was performed in five months by Morris & Cummings' scoop dredger, working in two large shafts, dipping into the water at the bottom of each pier above. When hard soil was met with these shafts were shut, and the excavation performed by manual labor under compressed air. In the New York caisson the total number of shafts was nine. The blowers worked very well, and progress considerably; they had to be discovered by boring, and shifted or broken before the caisson reached them. When under 25 feet of water they could be blown up; this enabled the rate of progress, which had been 6 inches per week, to be doubled or trebled. When  79 the caisson had reached a compact soil, it was possible to reduce the pressure to two-thirds of an atmosphere in excess of the normal pressure, and water had occasionally to be poured into the open shafts to maintain the level of water in them. By frequent renewal of the air, a supply was furnished for one hundred and twenty men and for the lights; and the temperature was kept nearly constant throughout the year at 60° within the caisson, whilst in the open air it varied from 50° to 80°. As the load increased as the caisson went down, the roof of the Brooklyn caisson was eventually supported by seventy-two brick piers, so that the caisson might not become deeply embedded in the event of a sudden failure of air in the New York caisson two longitudinal partitions were added, which served the same purpose. In the silted sand which was frequently met with, a discharge pipe, up which the sand was forced by compressed air, proved very useful, discharging a cubic  80 yard in about two minutes. The New York caisson (170 feet by 102 feet) was sunk in five months; the earthwork re- moved amounted to 25,000 cubic yards. The cheapness of wood in America per- mits a much freer use of it than there could be attained in Europe. When the watertight nature of the lower soil in the foundations of the East River bridge is considered, coupled with the inconveniences experienced in work- ing under compressed air, as shown at the St. Louis bridge, it is probable that in some future large work it may be possible to commence sinking a large caisson with compressed air, and after a better stratum is reached open all the shafts. The operation could then be completed by pumping out the greater amount of water that might come in, and excavating in the ordinary way, as is often done in England, on a small scale, where the excavation to sink the cylinders to a water-tight stratum is per- formed by divers. If, as M. Moreauilbe suggests, the air-lock was placed close  81 over the working chamber, or even in- side it, which would save constant alterations and allow of its being 'of larger dimensions', it would be desirable to have a door at the top, so that in the event of an accident the men might run up the shaft without the delay occasioned by passing through the air- lock. At Bordeaux the air-lock was formed by fixing one circular plate at the top and another at the bottom of one of the ends of the casting cylinder, so that it was unnecessary to remove it each time that an additional ring was added. To save loss of air the air-lock should be opened very seldom, or made very small if required to be opened often. The cylinder thus had an annular form (Fig. 18) with two com- partments C, C', each having an exter- nal and an internal door. One compart- ment was put in communication with the interior of the cylinder by a perforated material, whilst the other was being emptied by the outer door, so that the loss of air was diminished without any  A diagram showing a double air-lock with one large and one small compartment. The large one being only opened to let gangs of workmen pass, and the small one just big enough to admit a skip and to contain a little crane for moving it. By having a small air-lock opened frequent- 82 Fig's 16. ARGENTEUIL interrogation to the work. Sometimes a double air-lock with one large and one small compartment is used; the large one being only opened to let gangs of workmen pass, and the small one just big enough to admit a skip and to contain a little crane for moving it. By having a small air-lock opened frequent-  83 ly, any sudden alterations in pressure are diminished. A more complete ar- rangement was adopted at Nantes (Fig. 20). The air chamber is placed on the top of the double shaft in which the skips worked, having at one side a crescent-shaped chamber, $a$, serv- ing to pass four men, and also on either side two concrete receivers, $d$, $d'$, having doors above and below. There was also a short balance weighing machine fitted into the foundations, and a box, $b$, $c$, holding a little wagon which emerges at $c$ after having been filled from an upper door, $a$. This last contrivance resembles that devised at Vichy by M. Moreaux (Fig. 19). The cast-iron box $L$, $N$, going Fig. 19. across a segment of the air chamber, has three orifices, $L$, $M$, $N$, and a drawer with two compartments slides inside it. If these compartments are at $M$ and $N$, 83  84 the left one at M is filled whilst the other at N is emptied. Then by a rack movement the drawer is pushed back till Fig. 20. 40 mm NANTES the compartment to the right comes to the center of the box, that is to say, into the air-lock, and the other is emptied outside at L. At Rotterdam, M. Michaëlis put a little inclined trough at the bottom of each box, and closed it at each extremity by a valve, so that it both formed a little independent air-lock and also a shoot for the excava-  85 tion. Mr. Smith employed the same sys- tem at the Omaha bridge over the Missouri. By not permitting the earth- work to enter the principal air-ducts, it was possible to keep them glassed bully-eyes clean, by which both the day- light was admitted and at night the light was thrown from a reflector. The use of lamps inside, smoking and giving a bad light, was thus dispensed with. The Author next proposes to give some details of the new foundations constructed by the help of compressed air. At Moulin cast-iron cylinders, 8 feet 24 inches in diameter, with a filling of concrete and sunk 33 feet below water into mass, cost £12 18s. 6d. per lineal foot, or £24 for one cylinder. For £60 18s. 6d. for sinking and concrete. At Argenteuil, with cylinders 11 feet 10 inches in diameter, the sinking alone cost £2 18s. 2d. per lineal foot, and one cylinder sunk 30 feet 6 inches in bur- ned and nined house, and at Orival, £7 12s. 3d., where the cylinder was sunk 49 feet in twenty days. At Bordeaux, A diagram showing a cross-section of a compressed-air foundation.  86 with the same sized cylinders, a gang of eight men conducted the sinking of one cylinder, and usually 34 cubic yards were excavated every twenty-four hours. The greatest depth reached was 54 feet below the ground surface at high water. In the regular course of working, a cylinder was sunk in from nine to fifteen days, and the whole operation, including preparations and filling with concrete, occupied on the average twenty-five days. One cylinder cost £100, a pile cost on the average £3.32, of which £200 was for sinking. M. Morandière estimates the total cost of a cylinder sunk like those at Argenteuil, at a depth of 50 feet, at £1440. Considering also the cost of piles of masonry and wrought-iron caissons of excavation; the foundations of the Lorient viaduct over the Soirff cost the large sum of £4 19s. per cubic yard, owing to difficulties caused by the tides, the labor of removing the boulders from underneath the caisson, and the large cost of plant for only two piles. The founda-  87 tions of the Kohl bridge cost still more, about £5 16s. per cubio yard; but this cannot be regarded as a fair instance, be- ing the first attempt of the kind. The foundations of the Nantes bridges, sink 56 feet below low-water level, cost about £200 per bridge; but the aver- age cost per pier was as follows: Caisson (41 feet 4 inches by 14 feet 5 inches), 50 tons of wrought-iron at £24 1,300 Cofferdam, 8 tons of wrought-iron at 21s. 9d Excavation, 160 yards at 16d. ed. Concrete, . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 340 Masonry, plant, etc. 384 £3,390 One pier of the bridge over the Messe at Rotterdam, with a caisson of 222 tons and a cofferdam casing of 94 tons, and sunk 75 feet below high water, cost £14,600, including the cost of the pier itself. The Visby bridge has five piers built on caissons, 34 feet by 15 feet, and the abutments on caissons 26 feet by 24 feet. The foundations were sunk 23 feet in the ground, the upper portion consisting of slingle and conglomerated gravel, and  88 the last 10 feet of marl. The cost of the bridge was as follows: Interest for eight months and depreciation £ Cost of plant worth £4,000. 800 Cost of preparatory, approach bridge and staging. 1,907 Caissons, No. 7, 100 tons at £23 6s. 8,813 Sinking. 2,017 Concrete and masonry. 2,017 Contractor's bonus and general expenses 1,854 The cost per cubic yard of foundation below low water was £3 8s. 7d., of which the sinking alone cost 1s. 3d. in gravel, and 19s. in marl. At St. Maurin the cost per cubic yard of foundation was £3 8s. 6d., exclusive of staging. The Author believes that the subject of tubular foundations at some length, because they are the most effectual means at the disposal of engineers for carrying foundations to great depths by low water, but where such considerations render it desirable to adopt pumping or dredging when possible; but compressed air is very serviceable where beddings or

Interest for eight months and depreciation	£
Cost of plant worth £4,000.	800
Cost of preparatory, approach bridge and staging.	1,907
Caissons, No. 7, 100 tons at £23 6s.	8,813
Sinking.	2,017
Concrete and masonry.	2,017
Contractor's bonus and general expenses	1,854
The cost per cubic yard of foundation below low water was £3 8s. 7d., of which the sinking alone cost 1s. 3d. in gravel, and 19s. in marl.	49,890
At St. Maurin the cost per cubic yard of foundation was £3 8s. 6d., exclusive of staging.
The Author believes that the subject of tubular foundations at some length, because they are the most effectual means at the disposal of engineers for carrying foundations to great depths by low water,
but where such considerations render it desirable to adopt pumping or dredging when possible;
but compressed air is very serviceable where beddings or

 89 other obstacles are met with, or where, as at Vichy, the ground is conglomerated and unsuitable for dredging. In cases where the proper course to be adopted is a matter of doubt, the success at the Gardon and at the Gavarnie, owing to the aid of divers, if necessary, would encourage an attempt being made to dis- pense with compressed air, which at great depths, such as 100 feet under water, is attended with danger. The Tet bridge, moreover, furnishes an exam- ple of the difficulty of receiving water to compressed air if found indispensa- ble. In soft ground of unknown depth the best methods for making foundations are those already described; but it is sometimes desirable to try works to adopt more economical methods. Two distinct cases have to be considered — 1. Where the soil is firm, but liable to be scourred to great depths; 2. Where the soil is soft as well as exposed to consid- erable scour. Hégermotes gained a reputation by  90 his method of dealing with an instance of the first of these two cases at Moulin, where several bridges had been destroyed one after another by scour in floods, owing to the piles on which they rested being unable to penetrate far enough into the firm sand composing the bed of the Allier. Régemortes, in 1760, renounced the idea of finding a stable foundation far down, and built on the surface, rendering it secure from scour by covering it with a massive apron. The apron was of a uniform thickness of 6 feet (Fig. 21), A diagram showing a cross-section of a bridge foundation. The top line represents the original ground level. Below this, there is a layer labeled "MOULINS" indicating the material used for the foundation. The bottom line shows the final elevation after construction. was laid on the dredged and levelled bed, dried by diverting the stream, or, in some places, by enclosing it with timber and pumping out the water. The infil- tration through the bottom was stopped  91 by depositing a layer of clay all over, and then lowering caulked timber panels in it. This method has, however, been much simplified by the introduction of hydraulic concrete. The apron at the West Viaduct at Amsterdam consists of a layer of concrete, 4 feet thick, placed on piling, and covered with sheeting by sheeting. The apron of the Gustin canal bridge, constructed by M. Julien in 1829, is 60 feet wide, 5 feet 6 inches thick, and 1,640 feet long. The concrete was carried down to a depth of 114 feet at each end between two rows of sheet- ing (Fig. 21). Another example of apron was adopted at the Ains bridge (Fig. 22), with a single row of sheeting at each end, 264 feet from the facing of the bridge at the lower end, and 114 feet at the upper end. The lower or down-stream side of the apron was al- ways the most secured against scour, if the belief that a cavity would be formed below by the scouring away of the sand, but that above the currents would bring- down sand and fill up any hollows that  A diagram showing cross-sections of two bridges. The top section is labeled "Fig. 23" and shows a bridge with a vertical cutaway view. The bottom section is labeled "ALN BRIDGE (1864)" and shows another bridge with a similar vertical cutaway view. 92  93 might have been assured out. The in- vestigations however, of MM. Minard and Marchall on the floods of the Loire and the Allier in 1856 indicated that the upper end of the apron is most exposed to secur and requires most protection, as the river bed close to the lower end is protected by the piers of the bridge, but at this upper end the river bed is exposed to the full force of the current where the ob- structions of the piers produce whirl- pools. The apron of the Ain bridge con- tains 27.7 m², or 90, per square yard of clear roadway above water, as much as the bridge which it supports. In certain instances the movable bed of a river has been sufficiently consoli- dated at the site of a work by merely a thick layer of rubble stones thrown in, giving time for the river to take its final settlement during floods. Lastly, a movable bed can be consolidated by a wooden stockade; one of these was made, in 1820, below Amboise bridge, like the one Perronet had put down un- der the Orleans bridge in 1701, and both have stood perfectly.  94 The second case of a soil both soft and liable to scour has next to be con- sidered. Where considerations of ex- pense forbid going down to the solid, the following methods have been adopted. (i) The ground is sometimes consolidat- ed by driving a number of piles close together, or by covering it with rubble stones with or without fascine-work, so as to form a kind of superficial crust capable of being driven into the soil; however, generally advisable to break through the superficial stratum, and to produce a compression extending down a considerable depth by a large weight of earth, as was done for the railway bridge at Llanfair, in Glamorgan (South Wales), where there is a thickness of 69 feet of salt under 70 feet of water. A large embankment of sand was tipped in and inclosed by sheeting, within which close rows of piles were driven, and then a water-light caisson was lowered on a platform 34 feet below the water, in which the foundations were com- menced.  95 (2) Another method is to increase the bearing surface at the base by large footings, or by timber platforms, layers of concrete, bedding courses of masonry, or rubble stone. (3) The weight of the superstructure can be diminished by forming hollow cells in the masonry, or by using iron girders instead of stone arches. (4) In heterogeneous strata the weight must be distributed as much as possible in proportion to the bearing power at different points. (5) It is advisable sometimes to include the site of the foundations with sheeting, walls, &c., not only as a protection against scour, but also to prevent the running-in of the soil from the sides when a weight is brought on it. The Suspension Bridge over the Dordogne furnishes a good example of a successful surmounting of difficulties in foundations. The suspended roadway was made as light as possible; the piers were hollow and perforated cast-iron columns, resting on a stone base sup-  96 ported by piles from 40 to 62 feet long, and 2 feet $\frac{7}{8}$ inches apart. The abut- ments and anchorage masonry were built with arched openings and light invert, and the embankments at each end were of light limestone blocks arranged in rough arches so as to form hollow spaces in the mass. Although in this enumeration of the different kinds of foundations bridges have generally been chosen for examples, the methods described would be applica- ble to other kinds of piers, such as bridge piers, graving docks, and quay walls. The difficulties attending the laying of lighthouse foundations, and the means adopted to surmount them, are fully de- tailed in descriptions of these works. In sea works the chief difficulties are encountered where the sea breaks against the structure, and accordingly the methods of protection adopted do not come within the limits of this Paper. But the valuable addition to the methods of foundations used for these works by the introduction of con-  97 crete blocks, which can be formed of al- most any size, and deposited by divers, must not be overlooked. The effect of pumping or hammering action referred to by Mr. W. Parkes and Sir John Coode (vol. xxxvi., Minutes of Proceedings Inst. C.E., p. 340) is due to the immersion and erosion during the oscillation of waves. Perhaps to this cause may be partially attributed the fall of a quay wall at Vevey in the present year. This wall was founded with concrete blocks, and in metallic boxes resting on high timber piles. M. Croizette Desnuyers has framed a classification of the methods of founda- tions most suitable for different depths, and also an estimate of their cost each. These estimates, however, must be con- sidered merely approximate, as unfore- seen circumstances produce considerable variations in works of this nature. 

98	Percy cubic yard.
Foundations on piles.	Depth.
after compression	30 to 35 feet...13 to 18
of the ground	35 to 50 feet...18 to 30
Foundations by sink-	ing wells	35 to 50 feet...30 to 37
Foundations by pum-...	(under 20 feet)...18 to 18
pumping)	26 to 33) favorable circumstances...30 to 55
foundations under water	foul water...18 to 24
Foundations on con-...	(under 20 feet)...18 to 37
crete under water.	30 to 35 ft. small amount of air under favorable circumstances...30 to 49
Foundations by means of air under favorable circumstances	(under 20 feet)...18 to 24
Foundations by means of Lorrent viaduct...99	(under unfavorable conditions).	Bordeaux bridge...140
When the foundations consist of di-...
eonected pillars, or when above prices must be applied to the whole cubic content, including the intervals be- between the parts, but of course for an equal cost solid piles are the best.

For pilework foundations the square yard of base is probably a better unit than the cubic yard. Thus the founda- tions of the Vernon bridge, with piles  99 from 34 to 81 feet long, and with cross timbering, concrete, and caisson, cost £14 7s. 7d. per square yard of base. According to estimates made by M. Picquenot, if the foundations had been put in by means of compressed air the cost would have been £100 less. The foundation, not watertight, sunk down £19 19s. 2d.; with concrete poured into a space inclined with sheeting, £12 15s. 7d.; and by pumping £17 8s. 2d. per square yard of base. M. Demoyers gives the following recommendations with regard to the choice of methods: (1) In still water to construct the foundations by means of pumping for depths under 20 feet. In greater depths to construct ordinary works on piles if the ground is firm; or to be well ballasted by loading it with earth; otherwise to employ pumping, and if a permeable stratum is met with to build on it with a broad base. For important works, if the soil is watertight, it is advisable to adopt the method of pump-  100 ing inside a framing, carrying down the foundations to greater depths than 38 feet by the well-sinking method. If the soil, however, is permeable, dredging and concrete deposited under water must be resorted to; compressed air being employed for depths greater than 38 feet. (2) In mid-stream compressed air must be resorted to for foundations more than 38 feet below water. In less depths the foundations of ordinary works are put in by means of wooden frames if the nature of the silt admits of pumping out the water; but if the silt is permeable a mass of concrete is poured into the site enclosed by sheeting. When, however, an important work has to be executed, it is desirable to use pumps supplied with compressed air. In sections. If a permeable and easily-dredged stratum lies between the hard bottom and the silt the method of a watertight casing, with a dam at the bottom, should be adopted. To complete these recommendations open cylindrical foundations  101 must be included. These may be re- sorted to, instead of compressed air, when the soil is readily dredged or watertight enough to allow of pumping, and also frequently in the place of piles or the well-sinking method. The com- pressed air system is certainly a last resource, and capable to bed exposed to scour, and also either difficult to dredge or with boulders or other obstacles im- bedded in it. In conclusion, a chronological list of works is added to show at what periods the principal steps in advance were made. The system of rubble mounds is the most ancient; and dams of earth came into vogue in the seventeenth century. In 1500-1507, the "Notre Dame" bridge at Paris was built on piles filled with heavy rubble stones. In 1716 the Blais bridge was built on piles and a platform at low-water level. The method of constructing a foundation by means of an apron was introduced by Régnemortes at Moulin in 1750. At  102 the same time Labelye built the founda- tions of the old Westminster bridge by sinking caissons in the dredged bed of the Thames, a similar process having been adopted, in 1856, for the pier of the Tuileries bridge on the right bank of the Seine. In 1765 Des Essarts invented a saw for cutting off piles under water, which enabled a caisson to be deposited on piles for the Saumur bridge, a method thereafter adopted for the bridges at Paris, at Boulogne, at Brest, at Cherbourg, and Bordeaux bridges, and old Black- friars bridge was built in the same way. In the year 1818 Vicat discovered the properties of hydraulic mortars, and the adoption of a concrete foundation depos- ited instead of piles, led to the bottomless frame system with con- crete at the bottom, first used by Beau- demoulin for several bridges at Paris, and adopted for the bridge over the Cher. In 1833-40 Poirel employed for the first time artificial blocks of concrete at Algiers harbor. He also used caissons  LIBRARY OF CONGRESS 103 with a bottom of canvas for depositing liquid concrete into situ. M. Triger first used compressed air at the Chalons coal mine in 1889; and Dr. Potts introduced his system in 1845. The tunnel boring machines mentioned was next introduced, and under various forms is continually becoming more universally adopted. The following are the dates of some of the works for which it was used: Gravesend cofferdam. Mr. J. B. Redman. 1943 Bootham bridge. Mr. C. H. 1881 Sainsbury bridge. Mr. L. K. Brunei. 1854-57 Kehl bridge. Mears. Flour R. Denis and Vaugner. 1883-9 Charing Cross bridge. Sir J. Hawkshaw. 1860 Canon Street bridge. Sir J. Hawkshaw. 1883 Tunbridge Wells. Sir Charles Foxe. 1868 In 1867 Kennedy's sand-pump was used for the foundations of the Jumna bridge. The "boring-head" was used by Mr Leslie in 1867-70 at the Gorai bridge,  104 and at the same time Mr. Milroy intro- duced his "excavator." Lastly, between 1870 and 1873 the Americans laid the foundations of the St. Louis and East River bridges, whilst Mr. Stoney, by depositing huge blocks in the Liffey, and Mr. Dyce, by de- positing concrete in large tanks at the Aberdeen break-water, extended the methods of employing concrete in river and sea works.  "Any book in this Catalogue sent free by mail, on receipt of price. VALUABLE SCIENTIFIC BOOKS, PUBLISHED BY D. VAN NOSTRAND, 23 Murray Street, and 27 Warren Street, NEW YORK WIESEBACH, A MANUAL OF THEORITICAL MECHANICS. Translated by E. H. Cune, A.M., M.E. 1860. 18mo. 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By James Watt, M.D., M.R.C.S., L.R.C.P., F.R.S.E., Fellow of the Royal College of Physicians, and Member of the Royal Society. With 2 wood-cuts and 5 lithographs. 1 DODGE. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODGE. DODELLER (See DODELLER.) DOHERTY (See Doherty.) DOHERTY (See Doherty.) DOHERTY (See Doherty.) DOHERTY (See Doherty.) DOHERTY (See Doherty.) DOHERTY (See Doherty.) DOHERTY (See Doherty.) 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DOHERTY (See Doherty.) DOHERTY (See Doherty.) DOHERTY (See Doherty.)  D. WAY HORTON'S PUBLICATIONS MACCORD. A PRACTICAL TREATISE ON THE RUBBER VALVES, BY ECKERTSON—examining the various forms of rubber valves, and showing the practical processes of laying well and pipe lines, with the proper use of rubber valves in the different classes of work done in the steam-engine. By C. W. Mac Cord, M. E., and J. B. Smith, M. E., with drawings. Boston: The American Institute of Technol ogy, 1870. cloth. $3.00 POWELL. A TREATISE ON THE ENGINEER IN THE STEAM ENGINES INDUSTRIAL, AND THE DEVELOPMENT OF THE STEAM-ENGINE. By Charles T. Foster, Third Edition, Revised and Enlarged. Illustrated. cloth. $3.50 MCDONALD. A TEXT-BOOK ON THE LAW OF THE GAT-THERING OF HEATED AIR APPLICA TIONS TO THE PRODUCTION OF STEAM AND STEAM-ENGINE. By Charles T. Foster, Third Edition, Revised and Enlarged. Illustrated. cloth. $3.50 VAN DE GRAAFF. 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With Numerous Illustrations, with Hand-Drawn Plans, 8vo, cloth. $1.00 START. THE NANTWICK DAY DOCKS OF THE UNITED STATES. A Description of the Nantucket Dock Company's Dock and Engraving on Steel. Fourth edition. 8vo, cloth. 6.00 COLLINS. THE PASTIME BOOK OF DESPERAL AL- LOTMENTS, ETC., ETC., ETC., ETC., ETC., ETC., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., Etc., E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E tc, E etc 50 TUNNER. 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A Popular Treatise on the Steam Engine Applicable to the Milling Industry. By J. H. Ward, Commissioner U. S. Navy. 810 CLARKE. A Manual of Rules, Tables and Data for Mechanics, Engineers, Architects, Surveyors, and Others Involved in Mechanical Work. With Numerous Diagrams, Plans, etc., Etc. 100 JOYSON. The Art of Dress in Costu- mation: Time, Place, Season, Weather, etc. 75 DOUGLAS. A Manual of Manufacture, Me- chanical Machinery, and the Industrial Arts. 150 VON COTZ. Treatise on Our Debts. By Bernard von Kotz, Author of "Freytag's Tragedy." Translated from the German by the Rev. John H. Biddle, with Numerous Illustrations. 400 PLATHER. Manual of Qualitative and Quantitative Analysis for Students and Prof's. From the last German edition Re- vised and Enlarged by the late Professor Schubert of the Royal Bavarian Mining Academy, Translated into English by J. H. Biddle. With Eighty-Four Wood-Cuts and Illustra- tions. 300 FLYNNBURG. 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Military Academy, and Professor of Engineering at the U.S. Army School of Mines, Fort Leavenworth, Kansas; Corps of Engineers, Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, Kansas; Instructor in Practical Engineering at the U.S. Military Academy, Fort Leavenworth, SIMS: A Treatise on the Principles and Practice of Railway Construction and In- struction to Purposes of Railway Engineer- ing and Railways and Roads: By Frederick W. 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EARTHWORKS MEASUREMENT OR THE LAST EDITION OF THIS WORK, CONTAINING EXAMPLES AND LABORATORY METHODS FOR THE MEASUREMENT OF EARTHWORKS FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF THE PRINCIPAL EARTHWORKS USED IN THE UNITED STATES AND CANADA, FROM THE FIELD BY THE USE OF TABLES AND FORMULAE, WITH A DESCRIPTIVE TABLE OF The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of the Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of the Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of the Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of the Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of the Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of the Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of the Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of the Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of the Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. With a Descriptive Table of The Principal Earthworks Used in the United States and Canada from the Field by the Use of Tables and Formulas. HORNER'S TEXT-BOOK ON MEASUREMENT OF EARTHWORKS, BY MEANS OF MEASURING TILES OR TILES ON AN ARBITRARY SCALE (1000) FOR ALL PURPOSES WHERE PRECISE MEASUREMENT IS NOT NECESSARY OR POSSIBLE (1000). By J.W.Horner, Civil Engineer(s). cloth. CLEVERMAN'S TEXT-BOOK ON GOVERNMENT SURVEYING AS PERFORMED UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876), AS PERMISSIBLE UNDER ITS ACT (1876).  D. VAN HONSTRAND'S PUBLICATIONS. MIRRIE A TEXT-BOOK OF GEOMETRICAL DRAWING, with Numerous Examples and Exercises, for Schools. With Illustrations for Drawing and Painting. By William M. Burt, Esq., and by William H. Ambler, Instructor. Ninth edition, corrected. $4.00 MIRRIE GEOMETRICAL DRAWING. Abridged from the octavo edition, for the use of Schools and Academies. New edition, enlarged. 1865. $2.00 FREE HAND DRAWING. A Manual of Outrageous Tal Figure, and Landscape Drawing. By Mr. A. C. Hurd. Particularly Illustrated with Plates, Boards, &c. 50 AXIS THE MIRACULOUS FRIEND: A Colloquy between a Young Man and a Young Woman on the Subject of Love and Marriage. By John F. Hurd. 1863. $1.00 Drawing - Dyes - Electricity - Gilding - Glass - Gilding - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Jars - Instruments, Machines, and Processes for Drawing and Painting. By William E. Arno, M.R.S.L. 1863. $1.00 HARRISON MECHANICS' TOOL BOOK, with Practical Rules for the Suggestion of New Tools and Machinery for the Improvement of the Art of Machining. By Wm. H. Harrison, Esq., M.D., LL.D., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., &c., 15 JOYNER THE MACHINERS AND STUDENTS GUIDE TO THE ART OF MACHINE SHOPPING AND MILLING, with Numerous Examples of Machine Work, by Francis H. Joyner, With 16 Folded Plates, new, cloth. 20  D. W.A. BOSTON'S PUBLICATIONS. RANDALL, QUARTZ OPERATIONS' HAND-BOOK; OR, THE MINER'S GUIDE TO THE USE OF AND ELABORATED. Fully Illustrated. 1870. $0.00 SILVERSTEIN, A PRACTICAL HAND-BOOK FOR MINERS AND MINING ENGINEERS. Amended. By Joline Silverstein. 3d Edition. 1875. $0.00 BARRELS, SUBMARINE WARFARE, DIFFICULTIES AND OPPORTUNITIES. Description of the va- rious methods of submarine warfare employed in the War Methods of Submarine Warfare of the Civil War and the present war, with accounts of experiments made to deter- mine the effect of various forms of torpedo under Water. Also a discussion of the Of- fensive and Defensive Measures which may be adopted by the Submarine Vessel in con- frontation with other vessels, and in reference upon the use of torpedoes against ships, boats, and other objects on land, and also against mines and other obstacles on land and in piles and many wood-cuts. 1876. 5.00 Foster, Submarine Warfare. In Boston: Houghton Mifflin Company; New York: G.P. Putnam's Sons; and Corcora Books. By John D. Foster, U.S.N., 1876. 4to, cloth. 3.50 Hawley, The Submarine Vessel. Illus- trated in the House, Temple, and to sub- stitute for the "Submarine Vessel" by Quayleag. Also illustrated. 1876. 3.00 WILLIAMSON, THE USE OF THE BARRELS. (See on Surveyors' Manual.) For Engineers and Mechanics. By William H. Williamson. Illustrated. 1876. 4to, cloth. Hyppomotive, Part II--Hyppomotive Apparatus for Use in Mines and Tunnels. Gt. U.R.A. Major Corps of Engineers. With Illustrative Texts and Drawings. 15.00 14  D. VAN NOSTRAND'S PUBLICATIONS. **WILLIAMSON. PRACTICAL TABLES IN METRE MEASUREMENT AND CONVERSIONS, WITH THE USE OF THE BAROMETER. By Col. R. S. Williamson, F.R.S. 62 50** **BUTLER. PROJECTILES AND RIFLED CANNON. A Course of Lectures on the Theory and Practice of Rifling and Projection, with Practical Illustrations. By Capt. John S. Butler, Corps of Ordnance, U.S.A. 750** **BENET. ELECTRO-BALANCE MACHERIE, AND THE ELECTRO-MAGNETIC SCALE. By J. V. Benet, Chief of Ordnance U.S. A., Revised by W. H. MacHerie, 3 00** **MICHAELIS. THE LE BOURGEOIS CHRONOGRAPH, WITH THREE LITHOGRAPHED PLATES SHOWING THE PRINCIPLES OF ITS WORKING AND ITS APPLICATION TO THE MEASUREMENT OF TIME INTERVALS. By Dr. Michaelis, Ordinance Corps, U.S.A. 4to, cloth. 3 00** **SUGERT. THEATRES ON OPTICS of Light and Light-Beams, and on the Action of Light upon the Individual Pupils, By E. Nugent, With 16 Illustrations in Wood Engravings. 1 50** **PERCE. SYSTEM OF ANALYTIC MECHANICS. By Benjamin Peirce, Professor of Astronomy at Harvard College, and Professor of Logic at the University of Cambridge, 10 00** **CRAIG. WEIGHTS AND MEASURES: An Account of the Decimal System, with Tables of Conversions to Other Systems of Weights and Measures. By H.B. Craig, K.C., Square-Sizer, London. 50** **ALEXANDER. UNIVERSAL DICTIONARY OF NEW WORDS AND NEW EXPRESSIONS IN ENGLISH AND MODERN, reduced to the standards of the English Language, by the late H.L. Alexander under new edition, sc., cloth. 3 50** 15  D. VAN NORTLAND'S PUBLICATIONS. ELLiot. EUROPEAN LIGHT-HOUSE SYSTEMS. Being a Report of a Tour of Inspection made by the late Sir John Rennie, Bart., F.R.S., U. S. Engineer, at light-houses and other works of engineering and civil construction. 80 SWETT. SPECIAL REPORT ON COAL. By R. H. Swett. 300 COLQUHOUN. GAS WORKS OF LONDON. By Zerah Colquhoun. 500 WALKER. Notes on German Prophesies, 1650-1700. Translated from the German, by W. T. Walker. U. S. Navy, 8vo, cloth. 75 POOK. METHOD OF PREPARING THE LINEN AND LINEN-COTTON YARNS FOR THE MANUFACTURE OF COTTON YARNS FROM THE YARN OF THE LINEN AND LINEN-COTTON YARNS. On the Monmouth County Floor. By Samuel Pook, Naval Constructor. U. S. Navy, 8vo, cloth. 500 LAWRENCE. A Manual of Invertebrata, with Illustrations by Alexander Wallace. 200 ELLIS. A HANDBOOK FOR THE USE OF CON- STRUCTION ENGINEERS AND OTHERS IN THE MARINE, SHIPBUILDING, AND OTHER INDUSTRIES, Including Merchantmen, etc., with information on the Drafting of Plans and Drawings, and on Illustration, 8vo, cloth. 150 SCURRALL'S MANUAL OF THE ARTS AND SCIENCES APPLICABLE TO THE MARINE TRADES, Including the Construction of Ships and Boats, the Manufacture of Iron and Steel Articles, Pipes and Piping, and Hot Water Boilers, etc., with Numerous Illustrations by J. M. Turner. U. S. Navy Department time. Illustrated in every volume. 16 Turner's Dictionary of Elevations and Ornamental Architecture. By J. M. Turner. 8vo, Paper, $3.50. 375  D. VAN NOSTRAND'S PUBLICATIONS. WABEYLY. MILK ANALYSIS. A Practical Treatise on the Chemical Analysis of Milk, and Its Detractors, Examination of Milk, and the Prevention of Milk Diseases. By S. H. Wabeyly, M.E.C. 8 16mo. cloth. $1.00 RICE & JOHNSON. ON A NEW METHOD OF OR- ORIENTING THE SHIPS OF WAR BY THE USE OF THE TROPHIC COMPASS. With a Description of the New Trophic Compass, and a Table of the Angles of Elevation of the Sun at Different Latitudes, and the Times of Conjunction of Bearer of Velocities. By J. M. Rice, Esq., R.N.; W. H. Johnson, Esq., R.N.; Capt. J. F. Smith, R.N.; Capt. J. S. Higginbotham, R.N.; Capt. J. S. Navy, and W. Wooster Johnson, Esq., Prof. of Mathematics in the Naval Academy at Annapolis. 50 COFFEE, A TEXT-BOOK ON NATURAL AS- TRONOMY: Prepared for the Use of the U.S. Navy, by John Ladd, Professor of Astronomy, Navigation and Surveying, in the United States Naval Academy. 3d edition. $3.50 CLARK, A TEXT-BOOK ON THE ORTHODOX AND MOD- ERN ASTRONOMY... By Lewis Clark, Commodore U.S.N., with illustra- tions by woodcuts, including the Ter- restrial Globe. 3d edition. $3.00 ROGERS, THE GEOLOGY OF PENNSYLVANIA: By Henry Rogers, Ph.D., Professor of Geology of Pennsylvania College. 2 vols. 4to. $20.00 IN PREPARATION. WEBBIE MECHANICS OF ENGINEERING APPLIED TO MECHANICAL BUILDINGS AND THEIR EQUIPMENT FOR USE IN THE UNITED STATES AND CANADA. Translated from the latest German Edition. 2 vols. 8vo. 17  Vas Nostrand's Science Series. It is the intention of the Publisher of this series to launch them at intervals of about a month. They will begin to be sent out in the first week of January, time, fancy books. The subjects will be of an emi- nently scientific nature, and will be illustrated by a number of beautiful engravings--all of the highest charac- ter. Price, 50 cents Each. I. CHIMES FOR FURNACES, FIRE-PLACES, AND STOVES. By J. H. B. Smith. Illustrated. II. STEAM BOILERS EXPOSED. By Zerba Culture. III. PRACTICAL DESIGNING OF RETAINING WALLS. By J. W. H. Hurd. Illustrated. IV. PROPORTIONS OF PIANO ORGAN IN BRIDGES. By Charles E. Bender, C. E. Illustrated. V. TREATISE ON THE CONSTRUCTION OF W. F. Butler. Illustrated. VI. OVERHEAD BRIDGE AND CONSTRUCTION OF STONE BRIDGEWAYS. By Arthur Jacob. Illustrated. VII. SUBURBAN AND DUMPING PITS BY THE RE- SEARCHES OF JAMES S. Talcott, C. E. VIII. A TREATISE ON THE CORRODED ENGINE. By William Silliman. IX. FUEL BY W. William Sloman. To which is ap- pended a chapter on the use of coal in the United States, pared with coal: By John Norman, C. E. X. CHEMISTRY OF THE OXYGENATED PRODUCTS OF the Fossil Fuelled by the French of Mallet. Illustrated. XI. THEORY OF ANGUS: By Prof W Allen, of the Washington and Lee College. Illustrated. 19  D. VAN NOSTRAND'S PUBLICATIONS. XII. A PRACTICAL TREATISE OF VOOGDAM ARCHES. By J. J. Atkinson, M.A., Ph.D., F.R.S. Illustrated. XIII. A PRACTICAL TREATISE ON THE GATES MET WITH IN COAL MINES, AND THEIR APPLICATION TO THE PRODUCTION OF COAL GAS. By J. J. Atkinson, M.A., Ph.D., F.R.S. Illustrated. XIV. FRACTIONATION OF AIR IN MINES. By J. J. Atkinson, M.A., Ph.D., F.R.S. Illustrated. XV. The Use of the Air-Compressor in the Production of Coal Gas. By J. J. Atkinson, M.A., Ph.D., F.R.S. Illustrated. XVI. A GRAPHIC METHOD FOR SOLVING CERTAIN QUADRATIC EQUATIONS BY THE USE OF CURVES. Illustrated. XVII. The Air-Compressor and its Application to Power. By W. H. Corfield, M.A., of the University College, London. XVIII. BREWING AND THE BREWER'S ART. By John B. Mcmaster, B.A., of the University Col- lege, London. XIX. Strength of Beams Under Transverse Loadings and Shear, Author of "Theory of Arches." Illustrated. XXI. The Air-Compressor and its Application to Power. By John B. Mcmaster, B.A., Illustrated. XXII. Safety Valves by Richard H. Bosel, C.E. XXIII. The Knochenhauer's Book on the Theory of Machines, by John B. Mcmaster, B.A., Illustrated. XXIV. A PRACTICAL TREATISE ON THE TEETH OF STEEL AND CAST IRON MILLING TOOLS AND MILLING CHUCKS, With a Chapter on Odontographia. By S.W. Robinson, Prof. of Mechanical Engineering, Illinois Institute of Technol- ogy. 19  D. VAN HOUTEND'S PUBLICATIONS. XXV. THEORY AND CALCULATIONS OF CONTINUOUS HEATERS. By Maxmild Mertman, C. E. Hesse- dorf. XXVI. PRACTICAL TREATISE ON THE PROPERTIES OF CAST IRON AND STEEL. By Prof. F. W. Kuhne. XXVII. OR BURNER INCENTIVATION AND CORROSION. By Prof. J. A. van der Heijden. XXVIII. OR TRANSMISSION OF POWER BY WIRE BRIDGE. By Albert W. Stolz. XXIX. Treatise on their Theory and Use, Translated from the French of M. Louis Poussin. XXX. TREATISE ON THE CONSTRUCTION AND MEASUREMENT OF INOX VESSELS. By Prof. Faustin Roger. XXXI. THE SANITARY CONDITION OF DWELLING HOUSES AND THEIR EFFECT UPON THE HEALTH OF THE INHABITANTS. By Prof. J. H. van der Heijden. XXXII. CARES FOR THE HEALTH OF THE WORKER FOR SAFETY AND AGRICULTURAL WORKER. Illustrated. * Other Works in Preparation for this Series. 20  THE UNIVERSITY SERIES. No. 1.—On the Physical Basis of Life. By Prof. T. H. Huxley, F.R.S., M.D., Ph.D., D.C.L., D.Sc., D.Litt., F.R.S.E., F.R.S.W., F.R.G.S., F.R.S.M., F.R.S.P.H.M., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., F.R.S.P.H.T., Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D. Bernal, D.Sc. Prof. J. D.Bernard, Ph.D. No 2.—The Evolutionary Theory of Life and its Relation to the Physical World and to the Origin of Species by Means of Natural Selection and Inheritance with Variation under Different Conditions of Life by Professors Weldon and Huxley at Yale College. No 3.—The Hydrometers of Evolution: Physical Proof that the Evolution of Man is a Fact by Professors Weldon and Huxley at Yale College. No 4.—On the Hydrometers of Evolution: Physical Proof that the Evolution of Man is a Fact by Professors Weldon and Huxley at Yale College. No 5.—Scientific Arguments on the Methods of Investigation in Biology and Medicine by Professors Weldon and Huxley at Yale College. No 6.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 7.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 8.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 9.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 10.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 11.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 12.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 13.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 14.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 15.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 16.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 17.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 18.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 19.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 20.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 21.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 22.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 23.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 24.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 25.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 26.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 27.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 28.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 29.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 30.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 31.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 32.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 33.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 34.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 35.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 36.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 37.—Lectures on the Structure of the Human Body: The Anatomy of the Human Body Illustrated by Professor Weldon at Yale College. No 38.—The Law of Diminishing Returns: A Study in the Limits of Natural Selection by Professor Weldon at Yale College. No 39.—Lectures on the Structure  VAN NOSTRAND'S Eclectic Engineering Magazine. LONDON, 500. MONTHLY TENNA, $5.00 per annum, in advance. SUBSCRIPTION PRICE, 50 CENTS. First Number was issued January, 1866. VAN NOSTRAND'S MAGAZINE OF ARTICLES, Original and Selected, as also Matter condensed from all the Supplementary Volumes, will be sent to Subscribers at the rate of SEVENTEEN VOLUMES NOW COMPLETE. NOTICE TO SUBSCRIBERS. Notwithstanding the fact that the first issue of this magazine was issued on January 1, 1866, no further sub- scriptions will be accepted with reference to any of the pre- vious issues. The next issue will be published on February 1, 1867. All new subscriptions will be supplied with Volume I to XVII inclusive, but no mail or express orders can be accepted prior to that date. New subscribers who desire to have their copies sent to them by mail will be supplied, upon in every case, with a subscription certificate, which will be supplied, upon request, in every case, with a copy of this notice. The magazine is made up of copious reports of the lead- ing works and institutions of the country, and of articles on subjects of general interest. It is the object of the editors to give a clear and concise account of all important matters, and valuable advice in procuring the engineering skill of the con- sumer. For this purpose they have secured the services of many eminent engineers. No person interested in any of the various branches of the science or art of engineering is asked to pay more than one dollar per year for a subscription. The magazine is published monthly at London, England, and sent to subscribers at New York City, at the rate of five cents per number. The price of single numbers is two cents each. The usual renewal periodical rent is at least four years. As a constant and continuation of current engineering litera- ture, this magazine is intended for the use of all persons engaged in the business or profession of engineer- ing of the kind in this country, it ought to have the con- stant approval and support of all those who are all interested in mechanical or scientific progress—from ages.  White background with no visible content.  HE UNIVERSITY SERIES VON THE PLAY, EASE OF LIFE, AND OF HUMANKIND, D.D.R.S. With an Introduction by John C. Edwards, Ph.D., Cambridge, Mass. Paper Covers - Price $1.00 THE COMBINATION OF VITAL AND PHYSICAL POWER IN MAN, M.D., of Rochester, N.Y., Paper Covers, Price $1.00 ILLUS. REGULARS FOR PHOTO-ASSE in relation to the human body. Hereditary Strains, F.A.B.O., pp. 78. Friedel's case. IV.-ON THE HYDROTHERAPY AND TREATMENT OF INFECTIOUS DISEASES, F.A.B.O., pp. 136. Friedel's case. Friedel's Case on the Me- chanical Treatment of the Inflam- mation of the Lungs, F.A.B.O., pp. 152. Paper Covers, Price $1.00. Eds. Curtis, Schen- ner, and others. THE APPLICATION OF ELECTRO-DICTION APPLIED TO THE ALIMENTARY CANAL AND THE DEVELOPMENT OF HUMAN ANATOMY FROM THE STUDY OF THE ANIMAL ORGANISMS, F.A.B.O., pp. 168. Friedel's case. The Application of Electro-Di- ction to the Study of the Ani- mal Organisms, F.A.B.O., pp. 184. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 200. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 216. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 232. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 248. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 264. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 280. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 300. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 316. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 332. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 348. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 364. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 380. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 400. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 416. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 432. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 448. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 464. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 480. The Application of Electro-Di- rection to the Study of the Ani- mal Organisms, F.A.B.O., pp. 500. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 516. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 532. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 548. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 564. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 580. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 600. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 616. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 632. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 648. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 664. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 680. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 700. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 716. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 732. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 748. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 764. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 780. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 800. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 816. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 832. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 848. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 864. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 880. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 900. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 916. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 932. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 948. The Application of Electro-Di rection to the Study of the Ani mal Organisms, F.A.B.O., pp. 964. The Application of Electro-Di rection to The University Series